Info from licensor: Caressing a shark's nose basically makes it go to sleep. You can pretty much grab it and wave it around.
The nose is a particularly sensitive part of the shark and the sensation of rubbing the tip just feels nice to them. Nice enough that they'll face death to feel it. That distracts them from the fact that they're no longer moving/breathing, and they sort of pass out.
Sharks have to keep moving to continue the oxygen flow through their gills, even during sleep. When they stop, their brain starts to shut down, basically blacking out from lack of oxygen. So in reality, they are not so much hypnotized as they are half dead.
*I do not support harming animals in any way. Theses are very experience divers and know how to handle a shark while it's in sleep mode. They take everything into consideration including the time before you let them go. As you can see in the end where the shark wonders off.
Enjoy,