I've shot running game with a handgun, swimming snakes, anyway. I won't count the rabbit 'cause I was using a .410 contender, cheating.
I shot a charging dog once, was so fast I didn't really even have time to use the sights, just point shot him. He was pretty close, though, about 15 yards and closing. I also head shot wounded feral hog at about 10 yards with a .357 magnum. I'm no Bob London, but I do practice a lot. I AIMED on that hog, though, had time to bring the sights up cause he was hit hard and not moving with much speed, just moving forward and baring his teeth.
No, I'm not that great a shot, but I'm, I would say, above average only because I practice and know my guns. I never made it to master class in IDPA, only a slow expert time when I qualified last. I suspect this guy was similar, well practiced and knew his weapon. I submit that the handgun out of leather is MUCH faster on target than the long gun slung over the shoulder, even slung muzzle down as I like to do while still hunting so I can swing it up with my off hand in a hurry. Carried port arms, you're likely as fast with a long gun, but you'll have that gun slug if you're doing something with your hands like maybe fishing.
Anyway, I reckon you choose what you're most proficient with. Apparently, this guy knows handguns. Some don't. Some are better off with a long gun, shotgun, whatever. But, if you can gain some proficiency with the handgun, feel confident with it, it's a lot handier to take along for defense and todays modern megamagnum hand cannon calibers are plenty up to the task. I would imagine the X frame is a hot seller in Alaska and I'd be lookin' at 'em in 500 S&W magnum if I lived up there. That's gotta be the baddest of the bad with as much horsepower at the muzzle as a 12 gauge foster slug, 2600 ft lbs, and a lot better penetration.
Fruit salad? Not enough left, LOL.
http://www.youtube.com/watch?v=RoW8nHIVuRk