The Crash Course videos are legendary as much for their content as well as their host's sense of humor.
Each video covers a small slice of US history in a 10-15 minute chunk. The only down side is that they tend to be VERY fast paced, and if you don't know your "stuff", a lot of the humor may go over your head... or worse, you may mistake the jokes for legitimate history! Still - useful and fact filled... and fun!!!