Beet.TV has a few interesting interviews on video search:
How Video Blogs are Searchable: Six Apart's Anil Dash Explains
Video Search Must Be "Universal," EveryZing's CEO Thomas Wilde Explains
Search is still unwieldy, but perhaps useful now for "national security" and data mining, which explains the roots of search services like EveryZing and Blinkx. Another part of the goal of these firms is to develop speech recognition to target ads in video clips; EveryZing shows you some inserted metadata now.