One of the items on the wish list for Google Video we posted last week was the ability to search only video material that can be viewed online. In other words, remove the video results where only thumbnail images are available.
Btw, Peter Chane, senior product manager for Google Video, told me last week that Google also plans to offer an option to limit to only viewable video. However, he was unable to offer a timetable for its release.
Poscript Two: The syntax to limit your search to only thumbnail images and transcripts, appears to be [source:tv].