I've often wondered about police who expect everyone to be able to put his hands together behind his back for cuffing.
For example, men with shoulder confinement issues are unable to do this. To make matters worse, this officer punched this man in the face from behind - one could almost call it a sucker punch. He's not allowed to do that, and there's a price for breaking the rules.
I don't know what preceded the incident, and I don't know whether the victim has shoulder or elbow issues. However, I do know that if an officer ever pulled this on me, I'd probably grab the asshat's gun and pistol whip him with it. That's what you deserve when you're a self-important little runt who throws his weight around like Mighty Mouse on a steroid jag.
Police need to respect the physical limitations of their suspects. It's common sense.