I remember seeing something like this (a video search engine for the german parliament) at the Fraunhofer Institute in Germany a few years ago, but they were, ehm, 'cheating' by correcting the speech recognizers with human-generated trascripts and they needed a special client to access the database. This one is completely automated. No human intervention. And, best of all, works with your browser, has a simple google-like textbox, shows you the contexts around what you searched for in a clickable timeline view and does a karaoke-like word highlighting when the part of the video you selected is playing.