One thing I learned from doing jury service is that everyone has a different idea about what violence is. I'm on the MP's side here, but I was in a minority of one when I wanted to convict a young man for what I saw -- on video -- as definite GBH. The rest of the panel thought it was just the kind of thing young men got up to on a Friday night... I've never felt quite so much like a stranger in my own community. And I say that as someone who'd had to help deal with violent drunks and shoplifters on several occasions. The worst, by far, was a woman who was having a really good go at separating another woman from her eyes. I felt I couldn't let that happen, but when I got involved I found myself having to be a lot firmer than I expected in order to keep my own eyes.
I know that's not directly comparable, but I think what I'm saying is that there's no pretty way of stopping someone in their tracks if you believe they are a potential threat and you don't want to be the person who sat back and watched a disaster happen. If you're going to detain anyone you do it quickly and effectively, and that's what I see in the video. We all know it was a harmless situation and he probably overreacted now, but at the time he didn't and neither did anyone else there.
I do feel, however, that Field's nickname from now on should be 'Spock', given his ability to render someone harmless with a pinch of the neck.