It is sad to see that sort of thing happen. However, just because you have a fast bike doesn't mean that you have the skills to ride it fast - and even if you do have the skills to ride it fast it doesn't mean that it is safe so to do.
As has been mentioned before, he was taking some very bad lines around some of the bends. (The bike with the camera was not too wise with his (or her) riding either.) Coming into a bend on the wrong side of the lane for a good line around the corner, coming in too fast, braking while going round the bend, extra weight on the back, these are just a few of the things I noticed. There is probably more to it as well.