Reminds me of my first kiting experiences back in Canada. Must've been 13 y/o and fashioned a kite from a blue poly tarp, lines and wood handles. Could only do downwinders on the lake with the skates so had to skate upwind or get car rides from dad. Black ice doesn't happen very often as the lake needs to freeze quickly in no wind/no current and without any snow falls for many days so it becomes thick enough. If we were lucky we had black ice once every 4-5 years.
You can even see ice-windsurfers passed the 4 min mark!
I understand why there wearing helmets and not jumping that much
Bet it's as hard as hell if you had a bad landing on black ice 
