I imagine that the fan is supposed to be blowing air down the eustachion tube that connects the ear and the mouth, so, allegedly, blowing air through his ear to fan the flame in his mouth.
I admit that I didn't see the charcoal, though that is the most reasonable reason, but ti could be that he is using a mix of powdered chemicals that are catalysed by his saliva into a dramatic exothermic reaction. The fact that he poked a hole in the middle of his mouth shows that it's not any kind of magic, rather he knows what he's doing needs Oxygen to get the desired effect.
I'd be more impressed if we got to see what happened from the very beginning, IE what it was he was actually putting in his mouth. Apart from that, fire-in-mouth is fairly imprressive. /hard to impress/