One of the things you’ll find a lot of on YouTube, is people doing their own covers of K-On! songs. A lot of the time, you’ll see some guy playing the instrument of his choice with the original recording in the background. Occasionally, though, you may find this type of video where someone had the bright idea to either edit several of these individual covers together to form a full band video, or collaborate with several other people to create one.
Yeah, I know the singer on that last one is a dude.