Engadget has recently reported that Google now offers a service they call Google Video.
They are indexing the closed captioning data of some TV shows in the US and grab some screenshots from each show.
This is different from the video search services of e.g. Yahoo or Altavista, as it doesn't index files available from the web, but TV shows (which are mostly not available for download, yet).
I'm looking forward to further improvements of this technology...