The first appearance of Googles Video Search was mainly tracking US TV shows. Google uses captions to allow fulltext search for most programs. (According to the Telecommunications Act of 1996 section 713, all new programming made on and after January 1st, 2006 will be required to have captioning.) Now they added an Upload Service that allows you to upload videos to there servers https://upload.video.google.com

From the FAQ:We're still in the first phase of the upload program. Once we approve your video submission and enter the next phase, we'll send you an email (to the email address you provide) to let you know that we're ready to add your content to Google Video. Users will then be able to search, preview, purchase, and play your video.

So right now they only collect videos for testing, the client is Windows only and uses Internet Explorer, oh well...