There are are few critical seconds missing from this video (the camera man instinctively took shelter when things went pear shaped)
There are a few frames at around 54 seconds showing it nose very high pointing 180 degrees from initial direction and moving backwards and decending.
From this angle it looks like the tail was probably really stuffed into the ground and tail rotor and gearbox departed.
Below aerial video of the aftermath, including the extraodinarily graphic circular inscription made on the concrete.
http://youtu.be/AhOpnyaZMuE
Mickjoebill