He gets out, walks around the car, then drives off at a decent clip. I can only assume it wasn't a flat tire...if it was, he would have left his hazzards on and slowly driven to a safe place where he could have changed it.
It could have been sand, water, or oil in the road, but most likely he had too much load on the suspension going around the corner. A small bump in the road like a frost heave, or expansion crack could have upset the suspension just enough to cause the suspension to bounce off the bump stop or skip slightly across the pavement. From there, physics takes over. Even though the turn is relatively mundane, all it takes is something small to change the balance of a car.
He may have done a good job avoiding the guard rails, but he used poor judgment in driving that fast around other vehicles on an open and unpredictable road.
This is how it could have ended. We all know the turn at Nurburgring and if your suspension isn't tuned right you'll fly off the track when you hit the rough patch.