The guy who did these must be quite good in reality, as his timing with what's happening on screen is impeccable. I think that's what makes these videos really work, and so hilarious. That, and I love the fact that the drums only come in when they're actually shown on screen.
I figure this must be what guitar heroes sound like to people who aren't into their brand of music. Check out a couple, along with the originals for comparison:
Originals:
There are many more of these parodies to check out: just start surfing the related videos and you'll find 'em.
This, however, is an abomination... and I think I like it. http://www.youtube.com/watch?v=bdlScn4JpsY