As I said, I don't condone WHAT he did...however if you listen to the unedited version on youtube at the beginning you hear him explaining that He ordered them to stop and they took off. Anyone that has ever watched "COPS" on TV knows that LEO's get a HUGE adreneline boost if someone runs and it can make matters much worse.
It is often caled "contempt of cop" and while it still does not justify excessive force, ignoring a lawful order from an officer does escalate that situation.
If the skate boarders had simply ridden to city hall in protest (for skate board day) and stopped when the officer order them I would dare say the video would be much different. Running may not be physically fighting off an officer but it is in many cased considered resisting arrest.
Will the officer be disciplined? very likely. Would the kids have been "choked" of they had simply stopped when the officers ordered them to? Not in most cities.