Mirrorcle World was already sung at 21:35 JST, and then maybe MC lasted quite long, 20ish minutes would be my guess?
At least people were still telling how there had been no song for awhile when the time was 22:00. Also, I the think the broadcast itself only lasted 90 minutes and not two hours.
(info taken from one Ayu group at mixi)
@Luna62: I would think that a pay channel like TBSch wouldn't have commercial, but I can't know for sure. I wouldn't pay for something with commercials at least.