Interesting video.
I've shot off of my PH's shoulder before (with his fingers in his ear, and even used his head (he was kneeling) as an elbow rest on a particularly long shot. But I've never seen the elbow on the shoulder. And it for appears to be a fairly reasonable distance - not terribly long (although that can be deceptive on video). Frankly, it looked awkward to me - maybe the PH was too tall?!
I can only hope that the PH got to put his fingers in his ears. It didn't look possible though.
Last comment. I realize this hunter was experience - at least it says so on the video. The shot he took - from that angle - on a slab-sided animal like a kudu is a low percentage shot and not one I'd encourage most hunters to take. Not every forgiving.
Don't mean to sound negative, and apologies if it comes across that way.