I don't know the technical aspects of performing these tricks/stunts but why do you say he's guaranteed not to be harmed?
I'm not impressed with Blaine at all, primarily because his tricks are heavily focused on the video production of his work. Editing, camera angles, lighting and many other things are planned out beforehand. I'm more impressed with people who perform good magic on a stage, where we're sure that the audience hasn't been paid to look shocked and where the video camera angles aren't critical to the tricks. ..and I'm not impressed with his "bullet-catching". He's not catching anything. He's standing very still with a special device in his mouth while a marksman shoots the device. It takes guts to do that, but not talent. All the talent there is with the marksman doing the shooting. (oh, and show me something that wasn't done 36 years ago. He could try the old "escape from a straight-jacket gag, or the submerged-upside-down-under-water gag...). Talented magicians: the guys who fool Penn & Teller are much more talented, just not as well marketing. Blaine is a hack.
Personally, I am greatly impressed with regurgitating alive frogs, holding your breath for a WORLD RECORD, spouting pure gasoline from your stomach, standing in an ice block for 3 days, being buried alive for 7 days, standing in a glass case with no food for 30 days, taking watches off dozens of people without them noticing, bullet catch, etc. The guy pushes his body more than any magician EVER not named Houdini, and stays ahead of the science curve like madman Tesla. I prefer the the original, classical magicians. In that regard, no one can hold a candle to David Blaine.
