The Red Bull Crashed Ice Challenge is an invitation only event [I think]. Most of the racers are pro hockey players, and full protective hockey gear is required. Masks sense - it would be really easy for someone to run over someone else, given the speed and the slope, and given the legality of pushing and shoving among competitors. Pro level hockey players practice jumping over each other to avoid that. A lot of the other skating "Cross" events that do downhill skating probably have similar rules.
Notice how fast they stop at the end, so they don't run into the wall. Now that's a hockey stop.
It shows on the "World of Adventure Sports" broadcasts sponsored by Jeep, on the NBC sports channel. They also show things like dangerous kayak first runs, board surfers on very large waves, and pro skiers skiing down near-vertical slopes - they frequently end up temporarily buried in avalanches that they trigger. One of the things some people love about outdoor sports is that there are no artificial upper bounds - you either recognize how far you can go, or you don't.
I often watch the show, but one thing I don't like is that they only show bits and pieces of the competitions.