OP means Opening Post, or sometimes the person who wrote the opening post.
From what I've seen of your swing, very upright, I am suprirsed you are saying it is difficult for you. I recall a post of yours from about 2 weeks ago where you were saying the ORDER of how you do your backswing. Sounds like if this variant is better for you, you were working miracles getting so upright by lifting the arms later in the swing.
took a while to get rid of