Here's a question
The AA-12 is a Fully automatic 12 gauge shot gun. It is 50K for one and no available for civilian market. SO please tell me, how the heck does he have 2?! 
This guy is getting so many Youtube hits that he has put himself in a position of being a marketing tool. He can shoot the big AA gun and the shotguns because companies are paying to advertise on his YouTube channel. He uses some of the money he makes to rent/borrow interesting firepower to create new material, for which advertising money is generated.
The accent may be fake, but he has found a way to make money posting YouTube videos of himself shooting all kinds of interesting weapons. Good for him, it's the American Dream.