Some random thoughts from a participation trophy quality ex-participant:

• Crashed Ice is a series of races put on by Red Bull. The sport is more generically known as Ice Cross Downhill (catchy, right?) Anyway, here's their full list of races.
• The guys you see here are really damn good, very fast and crazy well balanced. If you catch earlier rounds you'll usually see more crashing and less smooth sailing.
• It's really not too bad on the knees. Most of the injuries I heard about were related to bad landings. Broken arm, shoulder surgery, sprained wrist (me, whew), and one hip surgery. Saw one broken collarbone, ouch.
• For Crashed Ice events they do keep medics in the tent and nearby the course just in case.
• For a race less than one minute long these things are exhausting.
  
• Landings are actually pretty easy. So are some of the insane slopes that scared the shit out of me. And the heights.
  
• The challenges are the jumps and rollers. It's tough to get used to gliding upward, you have to learn to keep your weight forward without digging in the toe for a faceplant. Fail to keep your weight forward and your feet are headed skyward.
  
• Most of the Crashed Ice tracks, like this one in St. Paul, MN are refrigerated. They seem to try and do one natural (non-refrigerated) track each year, this year it was in Finland.
• Refrigeration or no, these things get beat to hell. Soft ice is rutted up fast around corners and landings.