For teachers hoping to infuse multimedia into their classrooms, YouTube makes for an excellent starting point. Plenty of universities, nonprofits, organizations, museums and more post videos for the cause of education both in and out of schools. The following list compiles some of the ones most worthy of attention, as they feature plenty of solid content appealing to their respective audiences and actively try to make viewers smarter.
http://www.onlinecollegecourses.com/2010/10/20/100-incredibly-useful-youtube-channels-for-teachers/