What exercise is this (rotating upper body holding a 20kg plate)?

Question

One of the players in my favourite sporting team the (Go the All Blacks!) does this interesting rotating exercise. My question; I'm wondering what the exercise is called, what benefits would you gain from the exercise/ the muscles it affects and how to preform the right technique. From the clip it almost looks like some kind of strengthening for the core.

Please view Rotating and lifting heavy plates the exercise is at index 1.50 minutes.

Answer 1

Around the head plate drill......I've heard it call the plate crown also. Here's a link to the Men's Health version of it: http://www.menshealth.com/workout-center/e/around-the-head-plate-drill/27532