A real documentary would involve debunking, and since that won´t be allowed.... no documentary.
That's like saying, just because there is not much documentary about humans controlling body heat, wim hof can't do it. Of course he can, he turns up his body temp with his mind, big deal. For you it might be. Not for tibetan monks doing tummo yoga. Which of course anyone can learn. Just like african shamans can control their heart beat rates and can even stop it for prolonged time. they can learn it, so can you. And then you're surprised to see yogis submerged in water in a meditative state for days and then you wonder why they don't drown lol. Or just because there are not many documentaries about humans being able to withstand 220v or light up light bulbs by simply holding them in their hands, that means ma xiangang can't do it. Well of course he can. You can't. As long as there is chi and people like john chang can direct it any way they please (of which there is video documentation) I can't see why it can't be used as a source of energy in the body. You think you know and understand it all. learn a bit of humility.