Scary s**t. Just watching it looks like he was maybe having mechanical issues because he looked to remove his left hand to adjust something on the left side. His experience saved him from major injuries. He knew the best thing was to bail off the bike. Making those decisions in such a quick fashion at the speed he was going were incredible.
Edit-My initial reaction was completely wrong. His hand came off because of a bump and the wind forced him off the bike. It wasn’t his decision but it worked out well for him.