looks like a lot of fun in that video. the only problem i see is his legs aren't getting a workout which is the best way to stimulate growth. squats, deadlifts. he needs to find some heavy stuff to pick up using his lower body. also that workout would take a lot of discipline and would get tedious after a while. there is just so much more to offer in a gym setting with weights and resistance training.
he won't be able to out bench a typical gym rat or squat 350, but his upper body looks pretty jacked working those types of muscle fibers just like a gymnast would. btw gymnasts when they get older develop issues with tendonitis and wrist issues and inflammation from years of hammering away.. so that type of training isn't advised very often IMO, maybe do his workout once a week and stick to the gym otherwise.