Today I saw a bunch of videos of different people shooting what is called a .577 T-REX bolt action rifle. Also a single barrel .460 WBY.

Could someone explain who these people are and where were these videos shot? It looks like some shop/store somewhere . . maybe in the Middle East.

Also. . . this .577, on firing, doesn't seem to stay in most shooter's hands! What the hell is this cartridge and WHY would anyone want one?

Thanks much.