I've spoken to a few police officers since this happened in Manchester, all of them said the same thing really, that the force used was hard to justify.
The first kick could maybe be justified depending on what happened prior to the video starting, nut the head stomp in no situation can ever be used.
The officer clearly saw red, instead of making an arrest on the lad on the floor, cuff and securing, he goes off and takes down the lad on the bench.
It was pretty much agreed that for him to do that something has gone wrong before the video starts. I've got a feeling that the officer who had her nose broken could be his partner / girlfriend or someone he's involved with, hence the reaction.
Either way, he's out of a job and most probably will be charged with assault. But I suppose if I had broken a police officer nose in an airport of all places, I would consider my self lucky that I had a few bruises in places, no real injuries to show, rather then 4-5 bullet holes in my chest.
Try that in any other country and your dead mate.