Billy Corgan from the Smashing Pumpkins slipped onstage and fell back into the drum riser.  The audio is loud, and the video isn't great....but you can clearly see him falling.

He later Tweeted: "For those that saw me fall during Bullet, that wasn't a stage move or clumsiness, that was me blacking out and wiping out. I have no memory of falling against the drum riser and my guitar cabinet, but I can tell you I've got quite a good bruise and am moving slow."