I say this not only because the application has such strong appeal, but because the Carnegie Mellon group has the right idea about how to approach creating an information application. Informedia is a system that takes video presentations, such as newscasts, and creates a searchable video collection from them automatically. They do this by combining several kinds of information technologies in order to extract all levels of information from the original. They use speech recognition and natural language processing to create a text database from the narrative parts of the video. They capture words that appear on the screen, but aren't spoken, such as names of speakers.
Image recognition identifies people or scenery.
The user interface has many ways to identify and ask for what you need. Search on a typed-in query, plus the face of your subject. Examine a timeline of the clip. The query words are each identified by a different color wherever they appear on the timeline, so that you can find where they cluster, and start viewing from that point. None of these is a perfect technology, as the developers are the first to point out.