Those are hand picked cases when riders managed to save. They crash quite a lot for a period of a few seasons, especially in the wet. There could easily be another video where every rider crashes. So, to answer the question - neither.
Dang, I had to stop watching or lose all confidence! A fair number of those wobbles had no discernible cause. I can say that I would have lost it in some of those, so I'd say skill and luck played a part.