I’m quite puzzled by this, but as long as it works, why not?
He has uploaded many videos on this topic.
I tried his breathing technique today (breathing LESS air) and suddenly my feet felt very warm. My feet and legs are constantly cold, except during the heat of summer.
Yea… I’ll pass on this. 
Sounds like bad circulation, and a lack of exercise. Boots on the ground and start running. 
Probably a combination of these things.
Do sports outside.
Meditate and control breath at home.
And NEVER run on treadmills. They are known to shorten life.
Take up Martial arts, or go swimming on a regular basis.