This is what we professionals call The Batman Trick. We call this the Batman trick because in the old Batman television show, they would have shots of Batman and Robin climbing up the sides of buildings. Since they couldn't reasonably shoot them actually climbing up the side of a building, they had a better idea. What they did was make a floor that looked like the side of a building and turned the camera on its side. Then the actors just acted as if they were scaling a building. Don't fear for this guy's health because that's exactly what he's doing.
Look further "down" and you can see that that's not a pit at all. That's a hallway. We all learned from an early age that hallways don't go straight down. All is well, though he is laying on the ground so he could still get a disease or something.