The only way I could see this being a problem is if the kid had literally done nothing to warrant the guard's attention, and frankly, that seems rather unlikely, given his behavior during the video. What I saw was a dumb-ass kid putting up a fight with a security guard while his dumb-ass friends called the guards on. Whatever the reason for the arrest, the kid was acting inappropriately, and the guard acted according to his training (that was a fairly gentile take-down, and the kid wasn't hurt) and his job. The guard did nothing wrong.
Meanwhile, the kid was probably crying about how he did nothing and whining like that so as to gain support from the pedestrians walking by... and it didn't work, because they could see that nothing was all that off about the situation.
As for people complaining about the baton lash... the guard did not hit the kid, he simply whipped it into the ground as a warning to the friends, who were moving in as if to help the kid. That was also part of his training, by the way.
So: the kid was squirming and kicking/pushing in attempt to defy the guard. The guard took him down with as little violence as his training allowed for (and indeed, that was a standard take-down), and only used his baton as a warning to the other punks. Why you mad, interwebz?
Oh, right: because children are above the law, and are allowed to do whatever they want with no real fear of reprisal.
Edit: After reading the comments, I now know more about the situation, and it's clear that the guard was only doing his job. Resisting arrest, several threats against a security officer, and finally, a violent attempt at escape. Sorry, but that kid is CLEARLY in the wrong. hopefully, any lawsuit goes through and the kid is made to suffer the punishment for his actions. Probably a fine. Unfortunately, his parents seem like morons, so he won't likely learn his lesson.