Re: reverse breathing
Posture is very important. Why do you think there are so many positions in the video you posted?
*I* wouldn't do it lying down, but that's just me. I do it standing up and work at the same time on everything else I'm working on: centered on my feet, open in 6 directions (on inhale and exhale, duh), no tension in the joints (have to work this one all over again every breath), ki extending from hara through limbs and out to infinity, etc. etc.