It is very very easy for a good hypnotist to make it feel like you can't get up. Fuck man, I've made people think that they can't move their arms before, and I've only watched a few videos on hypnosis. I do it to myself on a regular basis when I want to get into a deep medetative state. Muscle catalapsy, it's VERY easy to do. It's just the ego thinks that it can't be "duped". You watch, there'll be some kind of subliminal flashing that you only just see, and certain suggestions about feeling very heavy, knowing that you could get up if you wanted to, but you just don't feel like it.