To me the video shows that Price had the upperhand (orprobably it was very even) until Kimmorley grabs his left arm, which allows White to land with his right. White then follows up with a second right, which does definitely land flush in the jaw, and does turn his head a bit, so it is possible that he is knocked out on his feet by this punch, but not all that likely. A split second later, Waterhouse grabs price and flings him off his feet and his head hits the ground with waterhouse landing on it at the same time. It is at this point you can see Price's legs straighten, as would happen when someone is out cold.
It was definitely a big punch, it possibly was (but probably wasnt) a knockout punch, but it definitely wasnt the greatest punch ever landed on a football field. That honour would surely go to Soloman hauomone whose ko of Dan Stains many years ago now, was the most devasting punch (or punches) that i have ever seen on a football field. It was actually Frightening to watch.
In all reality, the White punch only landed flush because Prices left arm was dragged down, and that cant be disputed. I dont really think white would have necessarilly even won the fight if his team mate hadnt been involved.