I find this whole discussing quite disturbing, and I'm honestly wondering what video the people supporting the guard in this thread watched.
Now, I want to speak my mind, but I don't want to get drawn into the name calling I see in a lot of these posts, so I'll just tell you what I saw:
For the first two minutes, I see a very large guard holding a small child in an unnecessarily painful hold. I *can't* hold my elbow that high over my shoulder, and although a 12-year-old is going to be quite a bit more nimble, it probably still hurts. At first I assumed the kid had been shoplifting or something, and I thought it was out of line. Speculating about what may have made this called for, I thought the kid might have attacked the guard, or someone else. When I then read the kid was restrained not for something as minor as being reckless, as we all were at that age, I was amazed. The guard was bullying the kid. Hurting him for no reason, when a normal guard would have simply held on to the kid in a non-painful manner.
Meanwhile, his friends are running around being little shits, and the restrained kid is probably shouting nasty stuff too.
Then, at the 2-minute mark, there's something I clearly see very differently from most people in this thread. The kid is trying to climb out of a painful hold! Most people here claim he is kicking the guard, but it's far to slow to be kicking! And you can see the kid trying to get his arms out of the guards arm.
I could go on, but on whether the rest is appropriate hangs on your interpretation of the preceding, and this is getting too long.
I also wonder why he was just standing there, and, at the end, dragging the kid off. A security guard is only allowed to restrain people under very specific conditions, usually to wait for the police. Is that what they were doing?
The reason the fact that the kid is 12 is not so much relevant in and of itself, but because it results in this: The kid is tiny, and the guard is huge. A man that big should be able to restrain a kid that small without having to resort to violence.
But the most disturbing thing is the people saying this is good because the kid needs to "respect authority". I honestly don't know how to respond to that without pulling some form of a Godwin. In democracies we are governed by 'Rule of Law', and authority in no way keeps people from having to justify their actions. Security guards have no special privileges, and he's either be right or wrong regardless of uniform.
Oh, and in a vain attempt to prevent to black-and-whiting so prevalent in this thread: I'm not saying the kid and his friends aren't behaving like little shits. I'm not saying they shouldn't have had some proper degree of punishment. I'm saying that the guard initiated violence with the painful restraint, that I don't think the kid was kicking the guard, but trying to get out of the restraint. I think if the guard had held the kid in a normal manner from the start, there would have been no violence.