There's something satisfyingly self-referential about watching talented musicians try to play their own music in Rock Band and Guitar Hero. Especially when they're worse than you.
Here's a list of every video I could find. Let me know if I missed any.
Anthrax's Scott Ian, "Madhouse" at Best Buy
"You suck. You're going to have to write easier songs... 20 years ago."
Rush, "Tom Sawyer," backstage at the Colbert Report
KISS's Gene Simmons, Tommy Thayer and Eric Singer, "Detroit Rock City"
(thx, Oscar)
Dragonforce's Sam Totman and Herman Li, "Through the Fire and the Flames"
My Chemical Romance's Gerard Way, "Dead"
Metalocalypse's Brendon Small, Tommy Blacha, "Thunderhorse"
Jonathan Coulton, "Still Alive"
Backyard Babies, "Minus Celsius"
Evile, "Thrasher"
Bonus Clips
Seether covers Radiohead's Creep in Rock Band.
Joe Perry from Aerosmith talks about the difficulty of learning Guitar Hero for guitarists. "I've talked to a lot of guitarists who've played this, and all the older guys get to the first basic level and then it splits off. Then your gameplaying skills come in, because you have to play the game like it's one of those other kinds of games."
South Park's Guitar Queer-O. "Real guitars are for old people."

Waxy.org is the sandbox of 
12:29 PM
FYI, here's Sleater-Kinney's guitarist's take on Rock Band:
http://www.slate.com/id/2177432/pagenum/all/
1:35 PM
Gene Simmons did this on his reality show with the intention of showing up his teenage son. It didn't go so well:
http://www.youtube.com/watch?v=7cuGI4zckSc
3:31 PM
This is totally Page Hamilton from Helmet wearing a pizza costume and playing unsung.
http://www.youtube.com/watch?v=alY43qMvxM0
4:07 PM
Aldous: I wish! When asked about Guitar Hero in this 2006 interview, Page said, "I think it's really cool, and they gave me the game, which I will give to my nephew who plays video games like he breathes oxygen. I've never been a video game guy myself, but I tried to play it... I'm really bad at video games, but it's cool as shit."
5:07 PM
Conan O'Brien's non-writing staff spent some time playing Rock Band during the writers' strike. Conan singing Sabotage as Edith Bunker is outstanding.
http://kotaku.com/340226/conan-griefs-rock-band-playing-staffers-does-wicked-edith-bunker
7:36 PM
Says a lot about the video game, and those who believe they have real musical talent, when you see the people who composed the song fail at playing it with a plastic controller. I hope this serves as a catalyst to deminish the egos of some crazed guitar hero fans I know out there. Not that it's a bad game, it just has bad followers.
1:19 AM
Brilliant post.
It is SERIOUSLY impressive that Evile was able to complete their own song (last video in the post). "Thrasher" is one of the hardest songs in Rock Band, without a doubt.
1:58 AM
ninjacowboy: Why would this make Guitar Hero fans feel worse? If anything, it shows that they can do something real guitarists can't.
They're just completely different skills, like being a Navy SEAL vs. mastering Counter-Strike.
3:37 AM
I didn't know much of musicians are getting meta with their music. But if it will make their music more creative and more lively then I think they should go for it. I am surprised that some guitarists as good as Joe Perry have a hard time with Guitar Hero.
/Kristen B.
Magnavox MDR515H Reviewer