[tremon]

That's the first clear footage that I've seen (i.e. from an angle not obscured by smoke). To me it looks like the plane touched down with a slight tilt to the right, then the rear landing gear buckled (possibly -- those might be snow dunes obscuring the actual position of the runway) causing the right wing to hit the ground and break off. Then the plane continued to slide on its side for a second before tipping upside down.

Others are saying the plane hit the ground quite hard, I have no frame of reference to judge that.