Stefanie Olsen takes a look at rumored video search projects from Google, Microsoft, and Yahoo in the article: Striking up digital video search.
She goes into some depth on what Google might be (-: up to, "Google has demonstrated new technology to a handful of major TV broadcasters in an attempt to forge alliances and develop business models for a TV-searchable database on the Web, those sources say."
Stefanie doesn't mention several of currently available products that offer video search on the web. We listed several of them (both free and fee-based) in the post: Searching Television via Closed-Captioning. Our post also lists a few companies working in voice-recognition search.
Two other tools services mentioning:
+ Feedroom.com offers video/rss feeds/search of news segments from local television stations around the U.S.
+ Blinkx is also doing work in video search.