Covered by "Reasonable Articulated suspicion" that the person has, or is about to commit a crime, without that they have no lawful power of arrest, nor can he be charged with a breach of the peace when resisting what under those circumstances is an assault.
I dont think the video is edited, rather than the bloke only started filming when it kicked off, but I doubt the guy was so worked up simply because he was politely asked his name, an this is not some snotty little smart arse with a chip on his shoulder but a bloke old enough to know the way of the world.
All "Charges" have been dropped and I will take bets the police will now pay out compensation.