Firstly my dearest sympathies go out to this man's family for their loss.
But this story just sounds too bizarre to be true to me. It is hard to picture this guy running much faster than 6 or 7 mph. Could he have really flown off of the thing with enough force to hit his head and be incapacitated? I've run on all sorts of treadmills, at gyms, hotels, etc and have never even seen someone have a bad fall let alone come close to death.
Does anyone have any perspectives here on what might have happened?