From the Government Documents Department...
For some people, C-SPAN is a cure for insomnia, but this cable network provides a wonderful service by recording the public proceedings of our government for all posterity. Now, you can access all every C-SPAN program aired since 1987, totalling over 160,000 hours of video on the newly created C-SPAN Video Library. The site is comprehensive and easily searchable . From the site:
"Programs are extensively indexed making the database of C-SPAN programming an unparalleled chronological resource. Programs are indexed by subject, speaker names, titles, affiliations, sponsors, committees, categories, formats, policy groups, keywords, and location. The congressional sessions and committee hearings are indexed by person with full-text."
Take some time to check out the site and you'll find video of the Iran-Contra Hearings, President Clinton's impeachment trial, and even the 2006 Radio and Television Correspondents Dinner featuring Stephen Colbert's humorous look at politics and the media. Practically speaking, you may find a video of the Congressional hearing you need to trace the legislative history of a particular statute -- a much more dynamic approach to research than poring over endless pages of text.
For more, take a look at this New York Times article: C-SPAN Puts Its Full Archives on the Web