First, did you know that YouTube has a video editor? I just found this out.
You can access more than 10,000 videos (from C-SPAN, PublicResource.org, Voice of America, Al Jazeera and others) via the CC tab on the editor. You can also tag your own content as Creative Commons, so that other users can incorporate it into their videos. (Check out Creative Commons if you are not familiar with their licensing.)