I did watch the first video in full; the other link, and three others in another post only address blood oxygen. I made no claims about CO2. I don't think wear

I did watch the first video in full; the other link, and three others in another post only address blood oxygen. I made no claims about CO2. I don't think wearing a mask will meaningfully affect the breathing of most people, but blood oxygen isn't meaningful in demonstrating as much. Passing out from hyperventilation is a second order effect of hypocapnia; the proximate cause is cerebral hypoxia, despite the blood being saturated.