Police use unneeded force all the time. Not all police, but police in general do.
I work in a mental health residential treatment facility and we use restraints, but this situation was handled horribly.
Like I said, the is at the very least poor police training. This kid was no threat. He was making a scene yes, but he was not a threat. Instead of deescalating a situation, they created a bigger one.
They obviously don't know how to use a physical restraint on someone, and they certainly don't know how to escort properly.
Police should be trained to deescalate individuals non-physically, not just how to cart people off for whatever reason. I have one of the lowest restraint records, because I've been trained (and actually use the training) of how to verbally deescalate people.
If police would talk to people in situations like this instead of trying to dominate by force, we wouldn't have some of the situations we do right now.
Now, in fairness, the kid was stupid, and Lucifer you're right, he wasn't arrested until he started resisting. He would have been better off pulling a Gandhi and just sit. He should have been calm in this situation, because he allowed the situation to escalate by losing his cool. While the police may have incited it, in part, he should have been able to not run around like a wacky wave inflatable arm flailing tube man screaming like a little kid.
Even peaceful non-violent resistence could have got him tasered, but at least that way, he's not adding fuel to the fire.