yeah there is definitely no trick behind them. The stunts serve two purposes. The main one, is he enjoys doing them, he likes to push the boundaries of the human body to see what we are truly capable of. and two (this is my own personal opinion) it keeps him in the public eye and sets him apart from other magicians. Why would laymen tune into abc for a magic special when they could watch mindfreak every week? To them magic is magic, but you add the potability of death, or even just the though of being able to see someone do something that has never been done before, and people will watch it.