Would seem that it was most likely a blank round that went off..possibly also part of the demonstration, just not when he expected...I imagine if he shot himself in the leg, that he wouldnt have continued the demostration...nor would he have been standing up afterwards.
Being a blank round in a real firearm, it would certainly have hurt his leg, hence the limp...also, it didnt sound loud enough to be a live round.
Twat for not checking though...dont trust an American Rasta with POLICE written on his T-Shirt...