I just noticed this morning something I had never seen previously on the Google search engine results pages. Perhaps this has been like this for several days but I am fairly certain that this is a test Google is starting. If you do a search in Google for metacafe, for example, you will notice that just under the result for metacafe, is a search box with the label "search metacafe.com." Rather than explain it too much, here are some screenshots.
So, here is the other thing that I noticed.... At first I though that this must be a test that Google was doing and had little to do with how sites are coded, etc... However, what I find interesting about it is that not all sites have this display option. I was able to find this for Youtube, MetaCafe, and Dailymotion. I did not see this for blinkx, blip, truveo, clipblast, yahoo video, and a host of others.
I will do some research to see how this is happening. Another interesting point is that you will notice when you conduct a search within the search box in the SERP, you will basically execute a Google site search within the video sharing site. IE - Keyword "site:metacafe.com"
My guess at the moment is that this may have to do with the Google video sitemaps and the parameter within whereby you can specify as to whether or not Google can embed your video within the SERPs.
Here are the other screenshots:
And of course, Youtube...