Xbox Music: 30 second clips?

I just got my dashboard update and was looking forward to giving the ad supported Xbox music a spin, only to find out that the 360's Xbox music only plays 30 second clips? Was I misunderstanding? I thought you got free, ad supported music for a certain amount of hours each month starting with this update. Is that just for W8 and WP8? That wouldn't make much sense. I am disappointed to say the least.