What he does is the ability to raise his body temperature and maintain it optimal condition even in freezing temperature. He uses the Qi in his body to control involuntary functions.
This is an ancient art called Qi Gong that is NOT shared openly to the public! There are a lot of fake masters out there claiming this and that. One of them is Jeff Primack.
I have seen another video where these Tibetan Monks are able to raise their body temperature 14 degree F more than their normal body temperature which the medical community say is impossible because your blood cells will slowly dissolve at those temperature.
Ahh.... the ignorance of Western Medicine and Science.....