Zach Braff on 30 Rock - Season 3 Episode 19 "The Ones"
That's totally him! It has to be!
I don't have much to go on except for the fact that it looks like Zach Braff. It's also the kind of random comedy regular watchers of 30 Rock have come to expect. If that's not Zach Braff then perhaps it's his evil twin brother?
You see what I'm talking about? That totally looks like Zach manning the drums during that “Black Widow” song. What do you think? Oddly, I don’t see his name in the episode credits. I even checked IMDB and didn’t see his name in there.