The butt plate while sitting down (at least for me) is not the problem. The problem is my thighs will push up my abdomen/torso, which in turn will push up the chest, which in turn will push up on the helmet.
I'm sure sitting for taller troopers is a slight possibility but for me and other vertically challenged troopers sitting in armor is a no no.
Agreeing to what was said before . . . trooping a movie and watching a movie are two different subjects.