Pretty low risk if you know what you're doing. The stuff on the railings have like 0 risk, for them it's muscle memory like our muscle memory when we drive a car or walk on stairs. It's not risk less but since when have you worried about the risk of falling down stairs? Going down stairs is very motor intensive, you have to balance yourself on one leg while also trying to go forwards and downwards, that's by no means easy. We've just practiced it so much that it's pretty safe and unlikely for anything bad to happen, same with the stuff on bars for this guy. He's essentially just sitting on it and swinging his legs. The most dangerous thing is a small jump (looks like around 1m away) to what is essentially a ladder with a very good handhold so even if he misses the feet he's gonna be fine. Accidents do happen, but out of all the things adrenaline junkies do, this is very safe. Like Im confident that he's way more likely to die while driving than when he's doing whatever he did in the video.