The Rock Band commercials are pretty funny. But they show zero game footage. That is, in my opinion, pretty dumb considering kids are going to be asking their parents for a $170 game.
Sure, the kids have seen the game and possibly played it at Best Buy or something, but showing some game play so that mom or dad sitting at home could see the game wouldn't hurt.
Or maybe it was a choice not to show game play as four people jumping around a living room playing a video game would just look silly in a TV commercial.