A few weeks back, I mentioned that YouTube and Google were indexing YouTube's closed captions and subtitles. In fact, YES - both Google and YouTube ARE indexing videos for text that is contained within closed captions and subtitles. In this post, I would like show you why you should be taking advantage of YouTube's closed captions feature for SEO, amongst other compelling reasons. Get ready, cause this is a really long one... If you dont want to read the whole post, skip to my video below.

Closed Captions, Speech-to-text, and Indexing Video Content

At ReelSEO.com we've talked for a couple years about various issues that exist with regard to search engines crawling and understanding online video content. We've also talked a bit about the testing of and usage of advanced recognition technologies to assist search engines it terms of attributing accurate, direct temporal metadata to multimedia content so as to better digest, index, categorize, and rank that content.

In Depth Look At YouTube Closed Captions   YouTube SEO and More closed captions srt e1278616181331 200x76 Direct temporal metadata, simply put, is time-based metadata that is related to the essence of the media content. Speech recognition analysis performed on audio or video content is one method that can be used to produce temporal metadata (e.g. timed-text, closed captions), which can assist search engines towards better "understanding" and cataloging multimedia content. Closed captions are more than just text displayed on the bottom of a screen to represent the dialog of a video. They can also include environmental sounds like birds singing, phones ringing, people knocking on doors, etc. They can include a note about when music is being played, where the scene is, when there is laughter and who is speaking.

In Depth Look At YouTube Closed Captions   YouTube SEO and More speech to text e1278619574813 200x145 Several companies have successfully deployed speech-to-text analysis models for use in online video. RAMP (formerly Everyzing) is one company that we've talked about in the past that uses patented speech-to-text recognition technology to extract textual meaning from multimedia content that contains spoken word. Their customers have seen first hand the benefits of using extracted temporal metadata for SEO. Blinkxand Truveo, both video search engines, have stated that they use speech-to-text recognition to help catalog video content. After all, the goal of a video search engine is to process as much information as possible to enable accurate and relevant search results - the audio track of a video is one piece of information that can be incredibly valuable to that affect.

Google's Focus on Closed Captions, Speech-to-text & Search

Google has also been hard at work at refining speech-to-text models for extracting temporal metadata within video. We've covered Google's attempts at building, refining, and launching solutions for speech-to-text analysis.

In Depth Look At YouTube Closed Captions   YouTube SEO and More goog 411 logo 200x37 Apr. 2007 - Google 411. Google launched a great free 411 call information service (you should try it, I use it all the time) whereby users can call 800-GOOG-411 to get free, automated directory assistance. Google stated publicly that their intentions for launching the service were entirely related to building a speech-to-text model that could be leveraged for better video search.

"Whether or not free-411 is a profitable business unto itself is yet to be seen... The reason we really did it is because we need to build a great speech-to-text model … that we can use for all kinds of different things, including video search." - Google's Marissa Mayer

Sept. 2008 – GAudio launches with YouTube speech-to-text for political campaigns. This has since been removed by Google but this was their first publicly available functionality to allow users to search through video content, in this case video content related to the 2008 presidential campaigns, based off words spoken within the videos.

Nov. 2009 - Google Rolls out automated YouTube closed captions (limited)

In Depth Look At YouTube Closed Captions   YouTube SEO and More youtube closed captions Mar. 2010 – Automated captioning for all videos (Beta – English only). Just as I predicted for 2010, YouTube rolled out machine automated closed captioning for YouTube videos using Google's speech-to-text recognition capabilities. As a result, it is now incredibly easy for YouTubers to upload a plain text transcript and have it automatically formatted into a closed captions file that works with the YouTube video.

PROOF - YouTube's Closed Captions DO Work for Video SEO

So, it probably comes as no surprise that YouTube and Google ARE, in fact, using the text within closed captions on YouTube to index YouTube videos.

Back in October of 2009, Mike Lees, a ReelSEO reader and Founder of Captionworld.co.uk, emailed me to show results whereby his videos were being ranked for terms only found within his closed captions and subtitles on YouTube. According to Mike, for his videos, he has seen views on some of his videos increase 10 fold after the addition of closed captions. While Ive known about this for many months now, I was unable to duplicate results myself until earlier this year. As a result of this discussion with Mike, I set out to do several tests to prove that YouTube was indexing the text from closed captions files. So, it has taken me close to 4 months to get this post up, but better late than never, right?

The following is a video I created to demonstrate proof that YouTube and Google are indexing videos for the text contained within closed captions on YouTube:

Notes and Observations:

I thought it might be worthwhile to mention several items I found in my tests.

  • First off, I think that it is interesting that in the example test here, the video was not indexed for "RSEOKW9", which is included within the comments on the video. I will need to do more research here but it appears that perhaps the content of the comments on YouTube is not being used for indexing videos. Of course, most YouTube comments are useless so perhaps this makes some sense.
  • Additionally, I find it interesting to note that YouTube is also not using the annotations. Of course, this makes some sense as annotations often are used to point to other videos and seldom contain useful information about the video being watched.

Transcripts vs. Closed Captions vs. Automated

  • For several of my YouTube videos, I noticed that indexing was not working on videos for which I had previously uploaded closed caption files. Initially, my thought was that it may be related to the format in which I uploaded those files (.srt). However, it is now my belief that YouTube was tinkering with this and it is possible that it was turned off/on at some point during the time that I uploaded my closed caption files (in late 2009.)
  • Since February, I have successfully been able to get indexed for text contained in uploaded closed caption files in any format. In other words, successful indexing was seen for closed captions uploaded in *.SRT (SubRip) and *.SUB (SubViewer) formats, as well as for a plain text transcript uploaded using YouTube's machine transcription to time-code the text into closed captions. This is worked for older videos where I replaced the closed captions with a new file.
  • As to the question of whether or not Google or YouTube is indexing only closed captions that are turned on by the user or whether or not they are actually using their speech-to-text to automatically index keywords spoken within all Youtube videos, it appears that at this point, only closed captions that are turned on by the YouTube video owner are being used for indexing. I did a test here using a video with a unique phrase of 3 keywords (with no results found) spoken clearly in the video. For this particular video test, I did not upload a transcript or closed captions file. Instead, I checked to see if the video would be indexed for the words that were spoken regardless. Additionally, I did check to make certain that YouTube's machine transcript was accurately picking up the 3 keywords. The test was unsuccessful so at this point, it does appear that both YouTube and Google Video search index and factor into rankings the keywords found in caption files but not (yet) the keywords said in videos without captions or transcripts. I.E. - this only works for closed captions that are enabled by the owner.
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Implications for Video SEO & YouTube Optimization

There isn't anything "groundbreaking" here, in the sense that one would expect Google and YouTube to use the text within closed caption files to index videos. However, it is always nice to know this for certain, and now we do.

As for rankings and weight, it is difficult to say at this point what weight might be applied to keywords found within closed captions. I did do a few tests whereby I uploaded a video with keywords stuffed in the closed captions file, and it did not appear to rank any higher for the keyword used. This was not a comprehensive test (few controls, sample size, etc...) so the results are anecdotal at best, but they lead me to believe that at this point, text contained within closed caption files does not seem to "trump" text found within the title, description, links, or tags. All that being said, it would not surprise me in the least if YouTube were to begin to place more weight on the existence of closed captions within videos. Additionally, it would not surprise me if they were to begin to use their speech-to-text algorithms to automatically index words spoken in all YouTube videos, regardless of whether a user enables closed captions or not.

At this point, we can safely assume that uploading captions files to YouTube, even when only using a text transcript, can helps videos rank for words that are contained within the closed captions. Closed captions act as yet another signal to the search engines to help them better understand the video content. Adding closed captions to YouTube videos may help with indexing and ranking for more long-tail keyword phrases. For more competitive keyword phrases, closed captions is just one of many factors that need to be considered as more of a holistic approach to optimizing YouTube videos. Of course, adding a transcript to the description field would accomplish much of the same, but there are many additonal compelling reasons why you should start using YouTube closed captions.

More Compelling Reasons for YouTube's Closed Captions

Not only is it compelling that closed captions can help with SEO, but additionally, there are arguably more important reasons to deploy closed captions on your YouTube videos - namely, 1) accessibility for the hearing impaired, 2) global reach with regard to translations, and 3) advanced Search Filtering.


In Depth Look At YouTube Closed Captions   YouTube SEO and More closed captions accessibility 300x298 Adding closed captions to a video may be one way in which to get some additional traffic by making the video accessible to those without sound-capable PCs (e.g. many office workers) or those with hearing impairments. Common web accessibility guidelines indicate that captions should be synchronized, equivalent to that of the spoken word, and accessible to those who need it.

On Youtube, closed captions can be turned on by default for users that need it and earlier this year, YouTube launched interactive transcripts for videos that have closed captions whereby a user can actually read the text transcript, which is highlighted in time with the video (see image at right.)

Translations = Global Reach

In Depth Look At YouTube Closed Captions   YouTube SEO and More closed captions translations 300x181 One strategy in having your videos reach a wider audience is to include captions and subtitles in multiple languages with your video. Adding captions and subtitles to your videos not only make your video accessible to those with hearing impairments, but adding them in multiple languages can help to drive additional traffic from non-English speakers and international audiences. You can also upload your closed captions in your preferred language, and then allow users to translate the captions using Google translate, as seen in the picture to the right.

Advanced Search Filtering

Both Google and YouTube allow searchers to filter searches for videos that only have associated closed captions. If you want your videos to be found by those users, you will need to enable closed captions.

In Depth Look At YouTube Closed Captions   YouTube SEO and More youtube google cc filter

How to Create and Publish YouTube Closed Captions

This post is already long enough, so rather than provide a detailed guide on how to add closed captions to YouTube, I will instead point you to our article from November titled, "How to Add YouTube Closed Captions, Subtitles & Translations." In the post, we list out several available tools and services that will help you with creating closed captions for your videos.

Here is a list of just a few:

  • DotSub - No fee, video subtitling site and service in a 'wiki' style. You can view, upload, transcribe and translate all right through the site.
  • SubPLYis a service that you can use to generate transcripts and closed captions for your video. Check out our review of Subply vs. manual transcription.

In Depth Look At YouTube Closed Captions   YouTube SEO and More adding closed captions 300x94 Perhaps the easiest way to do this today, is to leverage YouTube's automated machine transcription feature which allows you to upload a plain-text transcript of the video (no time-coding necessary). If you have a script for your video, you can upload this and Google will match the words in the text file with the audio to create closed captions that are time-based. If you do not have a plain-text transcript, you can use one of the services listed here, or you can download YouTube's machine transcription file, fix it for errors, and then re-upload that file to YouTube.

Conclusion - DO IT!

Either way, whether for SEO, accessibility, global reach, etc... I highly recommend that you start adding closed captions to your YouTube videos. Good luck with your video marketing efforts and as always, keep it "reel."

  • http://www.tangsworld.de/ Tang

    I do german CC on some english YouTube videos on my channel. So I actually have uploaded 2 srt-files: english and german. In embedded videos it has never been a problem to choose german als the default language, but Facebook always takes english as the default language. Off course you can switch to the german language withe the CC button, but that would be too much to explain. To show my german Facebook-Friends the german version by default, I am forced to switch of the english language file in YouTube. Never found a way around it til now. Do you have any idea?

  • JavierPetrement

    Now that we are stepping up our video SEO campaigns, your site offers a wealth of information. Will check out the different tools you mention for editing captions.

  • JavierPetrement

    Now that we are stepping up our video SEO campaigns, your site offers a wealth of information. Will check out the different tools you mention for editing captions.

  • Tang

    I do german CC on some english YouTube videos on my channel. So I actually have uploaded 2 srt-files: english and german. In embedded videos it has never been a problem to choose german als the default language, but Facebook always takes english as the default language. Off course you can switch to the german language withe the CC button, but that would be too much to explain. To show my german Facebook-Friends the german version by default, I am forced to switch of the english language file in YouTube. Never found a way around it til now. Do you have any idea?

  • JavierPetrement

    Now that we are stepping up our video SEO campaigns, your site offers a wealth of information. Will check out the different tools you mention for editing captions.

  • JavierPetrement

    Now that we are stepping up our video SEO campaigns, your site offers a wealth of information. Will check out the different tools you mention for editing captions.

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  • http://www.facebook.com/profile.php?id=100000776318950 Carlos Gonzalez

    What if you are NOT the owner of the video what program can you use to translate the video? or add subtitles?





  • http://www.facebook.com/profile.php?id=713182847 Yelena Kadeykina

    Great read as always, Mark and very helpful. We'll be testing it on our videos, I'll let you know how works for us.

  • Russell Dean Jensen

    This is all amazing but I'm still waiting for object recognition within images for SEO purposes. Google images is cluttered with irrelevant photos to the keywords that are being searched.

  • Youtube Marketing

    Hay dude! I wanted to say it's very nice brilliant information, I really enjoyed reading and learning your blog. You know your job. Keep it up good work :)

  • http://vidiseo.com vidiSEO

    Looks like SubPLY isn't offering a free service anymore. Wonder if that has to do with the "YouTube Ready" captioning certification.

    Personally, I find that creating a transcript in Notepad and letting YouTube do the syncing works like a charm. Thanks to captions, I now rank #1 on YouTube for "Face Melting Presentation". Tell me that isn't competitive. :)

    • http://www.reelseo.com/ Mark Robertson

      Matt, thanks for the comment. I agree that creating it in notepad and
      uploading it is quite easy. That is how Ive been doing it as well. Good to
      see you on reelseo.com commenting. Thanks Matt.

  • Critical Mass Prod.


    Thanks for the great read. As one of the recently announced "YouTube Ready" captioning providers, I just got back from the National Association of the Deaf conference where I was able to meet Ken and Naomi from Google/YouTube. Naomi confirmed that only the user-submitted captions are currently being indexed, as opposed to the machine-generated ones.

    I believe the thinking is that if a content owner takes the time to upload a caption file herself, it is more credible and therefore should have more relevance to search and should be included. I think they know the speech recognition still has some accuracy issues.

    Don Stephens
    Founder and Co-Owner
    Critical Mass Productions, L.L.C.
    Oklahoma City, OK, USA

  • danimal

    first off, mark, the word that you should have used was "alluded", not "eluded".

    getting beyond basic english skills, the real question here is not whether the closed caption files are indexed, but whether they have any significance in the ranking algorithms... you gave us examples with only six and 10 search results, which is statistically insignificant.

    in other words, getting captions ranked on page 38 of the google search results is a waste of time.

    • http://tampalocators.com/ Dave

      Danimal, how does it feel to be so correct? I appreciate the thought and effort that went into compiling this information. Perhaps you should get into content writing instead of criticizing another person's work? Thanks for the information, Mark. It always helps to stay abreast of Google's indexing activities. Often 'fact' begins as hearsay and rumor so I am glad to learn as much as I can from others who are continually experimenting.

      • danimal

        um, dave, Everett Sizemore covered this subject two months ago, so it's old news... the industry needs to see how well it works, not another how-to article.

        • Mojocam

          By all means, Danimal -- please do some tests, as Mark did, and post your results.
          We'd all be interested...as I was to read Mark's thoughtful and helpful article.
          Thanks Mark! You covered several interesting angles of this topic -- although as one critic rightly points out, you did not provide an exhaustive analysis of how to move one's video to the top of search results. Surprise! -- there's more to be said on the subject.

        • http://www.reelseo.com/ Mark Robertson

          Thanks mojo ;-) You stole the words out of my mouth for Danimal.

          There is certainly more to be said about the subject, and more that will
          change with time. Ill do my best to keep up with it and provide helpful
          insight when I can. At this point in time, it was important at first to
          verify that CC were being used for indexing. As for an exhaustive analysis
          of how to move one's video to the top of search results - we've done it and
          it certainly takes a lot more than simply adding closed captions - but that
          is another post altogether. Stay tuned for more and thanks again for your

    • http://www.reelseo.com/ Mark Robertson

      thanks danimal for pointing that spelling error out (ouch). I did address ranking algorithms and you should read the post before you tell me what information Im missing since I say almost exactly what you just did in my post.... I was a genetics major so Im well versed in the scientific method, and I dont believe I stated that anything was statistically significant - more obvious than anything. It would be a "waste of time" to do comprehensive testing for that ;-)

      • danimal

        obvious? what exactly do google.com pages with only six and ten search results prove? you specifically titled your post with the "SEO" moniker, then failed to deliver any meaningful research on how well closed caption text works for ranking purposes.

        "...may help with indexing and ranking" and "...can help with SEO" is idle speculation.

        while i do appreciate the how-to ground work that you did on the basics of closed captioning, what you need to do at this point is to follow up with some statistically significant research on how well it actually works for search engine ranking.

        • http://www.reelseo.com/ Mark Robertson

          Thanks danimal and I hope Ill impress you next time. This time, I loose. I do appreciate the comments though.

  • Chuck

    Great article, thanks. Just so I'm clear, to get the most out of CC and indexing by search engines should the CC function be enabled for the videos or do the search engines pick it up simply because you uploaded the text whether CC is on or not? Thanks.

    • http://www.reelseo.com/ Mark Robertson

      search engines are picking it up regardless. Thanks for the comment.

      • Greg Jarboe

        Great article, Mark. I like your test results. Lots of people have opinions, but few have test results.

        • http://www.reelseo.com/ Mark Robertson

          Thanks Greg. Always great to have you commenting on the site. Hope to see
          you soon.

  • http://www.captionworld-newquayholidays.blogspot.com Mike

    Great post Mark

    And thank you for the mention. Couple of things. I leave the Captions turned on, the viewer can turn off if they wish.
    Youtube have put the caption file under the description in a drop down box so its always live. As Mark said in the post. My viewer count's rose dramatically after captioning. and all my captioned videos now show up in an assortment of ten countries while the none caption ones are in 3 or 4. Its amazing to see the search terms being used some of which the key words are in the caption file. Try "Home made Spray booth" in Google search. Then check the video menu. Tarrant Rushton airfield, it appears on page two. and in the Closed Captioned Video's. Yes Closed Captions are a must. They do work. More than well worth the effort.

  • http://www.VideoLeadsOnline.com/ Ronnie Bincer

    I've been adding CC lately with the hope that it would help in VSEO efforts. Thanks for your efforts in your testing and publishing some of the results!

    Do you think it matters (yet) where and how many times the words are mentioned in the video (kinda like it matters where and how many times the words appear on the page in regular SEO)? I'm asking for more competitive terms than “RSEOKW5″.

    I also really like YouTube's interactive transcript, so I can watch the words go by when viewing a video. To me that is real handy in case there is any "instructional" text that appears in the bottom third space as part of the video... it doesn't get covered up when the video is playing yet you can still read along.

    Woof Woof Woof!!

    • http://www.reelseo.com/ Mark Robertson

      I dont think it matters how many times the words are in the CC - IE - it
      wont help. The tests that I did did not show any benefit from having
      keywords stuffed in the cc. meow meow

  • Everett Sizemore

    I did a similar test a couple of months ago with similar results:

    I look forward to our call next week


    • http://www.reelseo.com/ Mark Robertson

      Cool. I just read your post... Very much the same in the sense that i also did that 3 word thing... except mind was "balloon tall monkey." Talk to ya soon.

  • Jeremy Campbell

    This is very interesting. I wonder if Google will come up with an open sourced plug in like this for the open media player?

    • http://www.reelseo.com/ Mark Robertson

      well, not sure what you mean. Closed captioning is available in the their
      chromeless player. do you mean the interactive transcript functionality?

  • skoegler

    Adobe PremierePro has had TtS capability for some time, and CS5 now will take a script and synch it with the audio portion of the video. This makes for clean (perfect?) transcription since the text was first in the chain of production. Is this something that can be used for the closed caption enablement?

    • http://www.reelseo.com/ Mark Robertson

      absolutely. All you need is a text transcript and Google will take the text
      and time-code it using speech-to-text...

  • Nav Raj

    There is a video portal -videocrux.com which adds value to the professional video content by manual tagging and lets a user to jump to the exact scene. Here is an example video -http://www.videocrux.com/video/10786/Obama-inspired-Dorothy-gallery

    • http://www.reelseo.com/ Mark Robertson

      It's relative enough so Ill approve but not interested in self-promotional
      links. Next time please add something worthy to think about.

  • http://www.reelseo.com/ Mark Robertson

    Questions from Grant:
    What close-captioning service did you use? Or did you do it on your own (and how)?

    What's the Google tool you used to create a video with your search terms? (I remember seeing that earlier, but I forget where.)

    • http://www.reelseo.com/ Mark Robertson

      So - in this case Grant, I did the transcript by hand (since it was quick enough and I had a script to work from). I uploaded the plain text transcript and let Google do it's thing for CC. For the test, I also did this manually, creating both SRT and SUB files, as well as a plain text transcript.

      As for the Google tool to make the video with search terms - it is the Google search story creator - http://www.youtube.com/searchstories (click on "create your own")