Used to - there’s a 5+ year riding gap and i’m still not co-ordinating my legs and upper body balance the way I should be. Still, thinking about it, it seems like something worth re-experimenting with.
Up until UPD he’s changing direction slightly every half pedal stroke which would be normal. With Muni - i think long cranks emphasise the changes but his aren’t that long. My read was acceleration but it could just be his riding style.
I wasn‘t very clear; the quick wobbling movement I meant was induced by the terrain rather than the input by the riders. I‘ve experienced this behaviour myself every now and then.
I didn’t directly see it, but in sharp curves like here before the UPD I sometimes hit the 36" wheel with my knee protector what acts like a (soft) braking action. At the wrong time it amplifies UPDing towards the front.
Maybe his tire got a puncture?
This looks like a “Hand of God crash”. I have witnessed these a bunch of times with friends on bicycles, this is the first one I have seen on a unicycle.