When you are riding in unfamiliar territory, do your research. Sometimes off-road riding can stop you cold with things that you could not have predicted, like trees fallen across your path. Sometimes you just encounter a dead end with no clear path through. And other times, well, there's a cliff that you did not anticipate.
Many riders will disparage the "stay on the path" mentality, and I get it. Lots of us are explorers at heart and we don't want to be followers on the same old worn route. There's a thrill that comes with riding a motorcycle on ground with no other tracks, just like skiing through untouched snow. But we should learn from this rider's mistakes, and know that when there's a path through, it means other riders have gone before and most likely survived. If there's no path, it might be a sign that the route you're taking is not so passable.
Then there is the simple foundation, the essential reason why many of us ride at all: the thrill of speed. Riding a motorcycle fast is fun. The feeling of speed is amplified on two wheels, too, where we experience gyroscopic forces unlike anything we could accomplish in a four-wheeled vehicle. So, the temptation to go fast when there is no obvious obstacle is intense.
The rider in the video can almost be forgiven for hooning along this gorgeous, flat, visible-obstacle-free landscape… except for the whole "out-riding your sight lines" thing. Sure, there aren't any trees or boulders or roots or anything but the temptation of wide open green land.
And there's the catch. There's so much green that it all blends together. That rocky crag? It's invisible until the rider is absolutely on top of it. At that speed there's no avoiding the inevitable.
At least he was wearing a helmet. The original poster says he's recovering. Ride safe everybody.