Man go fat kid. But in all honesty he should have thought things through a bit. Slamming the guy head first into the pavement could kill or paralyze him. While I fully stand by his actions this could have ended with a manslaughter charge. Then again when I was in middle school I threw a bully through a book shelf and cracked a guys skull open (Accidently). Their are many times where I could have killed someone when I took things too far.
So I do side with the kid, but this could have ended very badly for him. I like how that girl stepped in to prevent that bullies friend from getting his ass whooped.
All he would have to do is get in front of a jury and say "I firmly believed that i was in imminent physical danger, and acted in self defense." For that charge to actually hold everyone in the jury would have had to sentence him, and you will be hardpressed to find 12 people where a single one won't side with him, especially given the tape.
He would have been fine and there would have been one less waste of oxygen in the world.