Another great tip from David at Open History - Google Video now allows you to post the HTML code directly to your site. This means you can easily blog great BBC documentaries like "Inside Nintendo"...
...handy academic materials like this short MIT video introduction to OpenCourseWare...
...or less educational materials like this Showtime documentary on KISS.
David also has a great History Channel video, "Ape To Man", over at his blog.
I've heard some mixed reviews on the new Google video store. I personally like the interface, although I certainly won't be paying $1.99 for old I Love Lucy episodes or $4 to watch the Knicks lose. In any case, the Google and iTunes video stores promote video on the web, which ultimately trickles down into free educational materials.
A number of universities are getting on board with video or "webcasts". MIT, Berkeley, and the University of Washington (UWTV) are all offering videos of courses and lectures. The Berkeley webcasts offer complete classes via RSS and UWTV has a large library that can be browsed by subject. A number of companies, such as Learner.org, are also offering free educational videos including these popular French and German video classes (Disclaimer: you have to sign-up and your computer has to be in the US or Canada to access the classes). If you're looking for more video, be sure to also check out the previously mentioned MediaSite and LearnOutLoud.com.
One more thing, Google Video now lets you download the free content, but use this tool to download from iFilm or YouTube.