This is a silly, nigh inaudible video of some Harmonix developers playing Rock Band. They mostly stink, I think—I’m not a Rock Band or Guitar Hero connoisseur—but as Kotaku points out, it’s hard to fault Harmonix completely.
First of all, this video was taken at the Nottingham GameCity3 event, whatever that was—it’s fair to assume that they all had a few beers in them. Unless you’re James Hetfiled in the late 1980s, you shouldn’t be mixing alcohol and guitars.
Second, the girl isn’t even an employee of Harmonix; it’s former Edge editor Margaret Robertson. That’s no slight against Edge, mind you, but her awful playing is in no way Harmonix’s fault.
Third, why hasn’t anyone made a Hop-Hop Hero Hip-Hop Hero (I leave the typo there to encourage you kids to stay in school, forever if at all possible) game? You’d think the big game publishers would be all over that.