One of my old jobs in the service. Watch his breathing get deeper and his cheeks get flush. He starts getting happy. This is to show the pilots the affects of hypoxia(lack of oxygen) so they can know what there symptoms are and correct before they die. "Gang Load" is turning your regulator on, at 100 % and at at emergency pressure. After he corrects, you hear the oxygen start to flow at emergency pressure and the fart sound is the gas flowing passed his face against his cheeks. Notice he goes back to doing what he was doing before. He was most likely off of oxygen at 25,000 feet during this class. I actually would get very blue around my eyes and around the beds of my nails. I wonder how many brain cells I killed in the name of science?