Some of those videos show a harness that goes around the skiers butt/legs that attaches to the ski rope, I assume to relieve stress off their arms. If there was a way in hell I agreed to 130mph skiing, there's no way in hell I would trust whatever breakaway mechanism was supposed to happen between this harness and the ski rope if I fell. In that 70 mile race, one dude fell. Interesting commentary around that point, and I'm sorry, I don't remember what minute it was, but dude was in pain.
In high school, when I was younger and stupider, I had a ski boat that would do 53 with just me in it. One day I was slaloming with either one or two people in the boat and I got brave and told the driver to open it up. I expect maybe 50mph. I fell, it hurt. That was the end of my day skiing. I didn't hurt anything seriously, but I didn't want any more that day.
As far as that blitz video, that water is smooth AF. Ideal skiing conditions if you weren't going 80 mph around the slowest turn.
At another point in the 70 mile race, one of the boats hits something and their speed is compromised. They supposedly clean the river, but what if the skier hit it instead of the boat? If you have 50 minutes of nothing to do, watch it. At one point, the river is so narrow, the ski ropes are in the trees on the bank going around a curve. There's also birds flying all around that I wouldn't want to hit at 80-139mph.
Sorry, I went down a youtube wormhole and as someone who grew up on the river and used to ski several times a week, this blows my mind.