I would film it... you need proof you know. What are you going to do, attack the cop? Call more cops? Use your words against a cop in front of a judge? Please tell me, PLEASE!
Call me crazy, but if I see my kid being harmed, no matter who it is, I am defending him. I dont care if it is a cop, or whoever. And if that means I get in trouble, so be it. However, my kids wouldnt do that because I teach them to respect and listen to the police unless they are being accused of something big. This kid obviously didnt respect the cop first by turning and walking away from them. Respect goes both ways.
Unless you are being detained, you DON'T HAVE TO SAY ****. Why do you think respect has to be given to people who won't respect you?
Again, the kid disrespected the officer first. And you are right, he didnt have to say anything but more often than not, the people who dont say anything either have a chip on their shoulder, or something to hide. Was the cop using excessive force, yes...but if the kid was innocent like he said, he should of said something. And yes, protect your rights but be smart to know when to do so and when it is worth it.