Some good discussion on impact and release here:
The golfer in video does seem to get a little more involved with trying to keep the left wrist flat for my tastes. Not to say that isn't what you should do (the left wrist has to stay flat in order to consistently hit quality golf shots), but to me it's more important to focus on the pivot. I paused the golfer's swing at impact and he's got a perfectly flat left wrist and is greatly compressing the ball. However, it's important to note that he's doing a tremendous job of pivoting with his hips at least 45 degrees open at impact.
I recently videotaped my swing and I found that I improved by leaps and bounds in just a two week span by finding a way to improve my pivot. I try to feel like at the top of the swing I'm trying to turn that zipper directly at the target while holding my arms and hands back. The problem *I* have with trying to manipulate a flat left wrist at impact is that *I* wind up getting the arms and hands moving too fast on the downswing. When I get the downswing correct, I can noticeably feel my club AND arms lagging way behind at impact. Basically, I want the thought of hitting the ball with my pivot instead of hitting it with my arms and hands. So the thought is "zipper at target, keep the arms behind."
But golf is a game filled with swing thoughts and feels that are purely subjective. So this video may work for you or my swing thought may work. Either way, you MUST pivot properly to hit quality golf shots consistently and in general you want to get the hips open at the target so the zipper is facing the target at impact.