I drive this road everyday, and I see the skid marks. It's right before a sweeping right hand. I can speculate a few things that may have happened:
He was in the left lane (5 lanes with a suicide lane dividing, 55mph posted speed limit). Right before where the skid marks are there is a side street on the right. Maybe he saw a car about to come out, got spooked, hit the brakes, and slide right across the road.
He could have just gotten spooked by the fact that the road was about to curve. I have seen people hit the brakes before the curve and they were only doing 45mph, so if this kid was really moving this could have done it as well.
Another possiblility, there is a traffic light right after the curve. I doubt this is what caused him to loose control, because you have to be looking WAY ahead, and I'm guessing he was looking at his speedo, or the guy he was racing, etc.
I actually see more people going UNDER the speed limit since they don't realize it's 55, but every once in a while you catch someone really moving.