This is a classic example of a barrel obstruction. A timing issue will generally not result in a catastrophic failure and if so, will cause a cylinder rupture. He likely had a misfire on the previous round and this is a video of the follow up shot.

It would appear that the timing of the cylinder was off and that the chamber was not in proper alignment with the barrel bore when the cartridge was discharged. If the projectile is obstructed and unable to exit the cylinder, the positive feedback between propellent deflageration rate and chamber pressure will escalate until something yields. In this case, it appears that the threads that secure the barrel to the frame were sheered off. This guy is lucky that the walls of the cylinder didnt rupture.

I'm not so sure the cylinder was off, because the primer is very small so if the cylinder was off the hammer wouldn't be able to strike the primer.

He's having a cartoon moment. I seen this happen on the Road Runner. Poor Coyote.!
Beep Beep

Looks like it may have been disassembled and put back together wrong