The officer is completely justified for many reasons. Granted skateboard is not a arrest able offense there may be other causes for his attempted arrest.. Disobeying an officer such as what the girl did. When an officer is in the process of "arresting" or detaining a person you should never attempt to come up behind them. In this day and age of people being sort of crazy cops must keep their guard up greatly. Think like he would be thinking.. Maybe one might attempt to go for his gun. Maybe attempt to strike him in the head so they can escape without getting caught. Attack in general and do other things. Granted they were teens and such there is still a good memory of what "kids" can do in this day and age. Police have the right to act as he did in that situation.. If you keep struggling with a cop when they tell you to settle down then you’re going to get a more aggressive tone then if you were to just be still, listen to what your told, and just be very respectful like you should to a person in authority.
Also yes skate boarding on public property or in parking lots should be illegal because they tend to grind on things and what if they fall on your car? You going to just sit there and say your sorry that they just put a nice dent in your hood? That is what skate parks are for and thats what tax payers have paid for..