Increasing blood flow to the extremities increases the amount of core body heat transferred to the extremities. Not witchcraft, or bullshit. Basic physiology and thermodynamics.
All this guy is doing is allowing his entire body to cool at a similar rate, rather than conserving core heat at the expense of extremity heat. The net result is that you can stay exposed to extreme cold for longer before frostbite, while sacrificing total survival time. Using this technique you'll die faster, but probably keep your toes if you live.
And then there's the hyperoxigination. If you breathe fast, your blood gets more O2. More O2 means a faster metabolism. https://www.ncbi.nlm.nih.gov/pubmed/15803488 Wim Hof carboloads, and breathes fast to burn more calories.
In simple terms, this guy is overclocking his body.
Doesn't make sense to me. Freezing temperatures freeze cell walls causing frost bite. There's no amount of mind control that can counteract that. I smell a rat.