I didn't listen to sound cause I am at work and this computer doesn't have speakers. But the guy used a skateboard. A swing like that could kill someone, and that ain't funny. Getting a broken jaw is one thing but a blow to the head with a skateboard is just wrong.
Even if I didn't know the guy who got hit with the skateboard I would break it up or call the cops.
If that was my friend getting hit with the skateboard I would have curbed that p.o.s. Then again my friends don't try and headlock people from behind...
Side note:
Nastiest fight I ever saw was at some WT bar in Laguna Beach called the Sand Piper, a guy got thrown into a window of a bar and his eye got cut open, grossest thing ever, the white part of his eye looked like cottage cheese hanging out.