You may have to watch the recoil twice. Try to follow the gun. This video is basically a 'show and tell' of a custom built handgun on a Thompson Encore (fancy version of the Thompson Contender). The Caliber? ...600 Nitro Express.
That's right...an elephant gun round in a handgun. The story goes that the guy that built it is some kind of custom gun maker, and built this as an exhibition piece. He took it to the range with him just to show it off, and the big guy that shot it (in the video) had been bugging the builder to let him shoot it.
Only until fairly recently (early-mid '80's IIRC) the 600 Nitro Express was hands down the biggest, nastiest, hardest hitting, and heaviest recoiling weapon you could buy.
It was designed for one simple purpose...to knock an elephant flat on his butt... IMO, it was really built as an exhibition piece for guys 'compensating' .. This cartridge is known for breaking collarbones, arms and shoulders...of the shooter!
In the gun world they use what is termed a 'recoil index' to give prospective buyers an idea of what a gun kicks like..
A 30-06 gets a rating of a 1.0, which for many people is about the limit of what they can shoot multiple rounds thru comfortably. A 243 BR is rated at like a 0.4, a 270 was like a 08, etc.
The 600 Nitro Express is at a 9.4................9.4 times more punishing power than a 30-06. And this one is in a HANDGUN, not a rifle (which is what the 9.4 index reference is based upon).