This was last Sunday on the European Ford Event in Holland during the sprint contest. It was actually the finals of the sprints where there were 3 Cosworth 4x4s, so all did several runs before on this day. They didn't need to stop, just slow down a bit a follow the banked track to drive around back to the start.
The run where the accident happened was his fastest run, so he might have had a bit higher speed at the finish than the previous runs. I'm not sure what happened exactly, but it seemed like both rear wheels locked up during braking, as I saw smoke coming from both rear tyres. As a result the back of the car slid to the lower part of the track, making the car go sideways a bit and out of control. I don't know why the rear wheels locked up. I would expect the abs to stop the lock up of the rear wheels, but it seemed like the abs didn't work.
I really feel for him. He is a nice guy and I think he can drive properly. Some comments made here are ridiculous, you weren't there, the video isn't very clear so you don't know what happened.