From what it looked like to me, he was making a sharp right turn....as he was sliding up high on the left side of the track....he overcorrected himself and went to the right side of the track really fast.....thus catching air under the sled and flipping him off. He went 90mph into a metal support (that area of the track is covered), and laid motionless. You could hear a "ping" from when his head hit the support. The video I saw stopped after he hit. No showing of them doing CPR etc.
Really not much to see. Sad, unfortunate event that as of now has been blamed on the Luger's inability/inexperience to steer the track and not a track deficiency.