The audio to this video isn't even perfect but you can still hear Zachary Levi (Chuck) sing "The Letter". He's quite good, no? Big, solid voice. He even does the dit-dits and the doodahs. Why do I get the feeling there's going to be a Chuck Musical episode after seeing this?
Also in the clip, Adrian Pasdar (Nathan Petrelli) and Jesse Spencer (Dr. Chase). This was from last weekend's Band From TV gig.