If that's not staff, and is in fact a student, I think that might be the "smoking gun". From the angle of the camera, that looks 6-10 feet off the ground... more than enough that if you land on your head, helmet or not, it's going to shatter your neck. Even if there is some sort of safety net, it would still probably do quite a bit of damage. Frankly, that looks damn dangerous, for staff or for the kids.