Looks fun. I kind of wanted to see him faceplant.
I clearly am outclassed by TJT, etc, and I have a fraction of his jumps / airtime. So I'm an amateur commenting... but looking at that video, you see how the guy is upside down but like keeps his legs bent, that exposes them to the "relative wind", and helps his positioning. It's really hard to keep your legs still and use them to steer you. I used to watch video of my early skydives, and I would always be kicking my legs all over the place, which makes it hard to "fly" (steer) in the air.
A normal skydive, at least at my DZ 20 years ago: drive an hour to the dropzone, get out, talk to everyone, sign up for a jump, do a gear check, put on gear, get someone else to check your gear before getting on plane, wait for pilot to be ready, board plane, climb slowly (I can't remember but felt like 20+ minutes) to 10,000 feet in a slow plane, sitting on your ass on the floor of the plane cramped in with multiple other skydivers, spend the 20 minutes of climb time debating why you skydive, do you really want to die do something stupid, is this really safe? Then they open the door, adrenaline skyrockets, jump out, experience free fall, do about 50 seconds of freefall, open your parachute, land, trek back to the DZ, pack your chute, then repeat. It's a process, and it can take many hours / days to get even 10 minutes of freefall time. So you do all that, you jump, and you do something stupid with your legs, you don't fly well, you rinse and repeat. ... In the tunnel, you can get 10 minutes of air time in ten minutes. So I imagine these guys get insanely good really, really quickly. Sucks that they are insufferable douchebags. Nothing sucks more than gatekeepers to really fun things. I imagine someone could get better in a wind tunnel in a few days than I did my entire skydiving career.
I'm sure there are accidental deaths in wind tunnels, but skydiving has far more. People bouncing, planes crashing, getting paralyzed doing stupid things under canopy, etc. I think at my age / family status / profession I'd just do the wind tunnel instead.