Typical oversteering accident, I would not be surprised if it was just after Brünnchen, a specially dangerous part of the track but so exiting to control the car at it's limits (and the ones of the driver itself !!), last time I was driving on the Nürburgring the track was time to time a bit wet and dry alternatively, very crazy to manage.
In this case, the track was dry but just a little too much throttle pushes any car frontally to the rails.
Edited: John reports that the accident speed was 70Mph, I'm surprising about that. In this case that could have been caused by a mechanical problem. No parts of this track is impossible to manage at this speed, otherwise the pilot was braking and the final speed before the crash was 70MPH.