He’s done this before, and you haven’t made a complaint???!
Passing snuff movies around is disgusting - IANAL but I would suggest that at minimum it would be Gross Misconduct and, probably, highly illegal and he should be immediately dismissed and possibly arrested.
However, I’m not a lawyer so I would contact ACAS ASAP, see https://www.acas.org.uk/ and log everything, inc. previous videos he’s sent around - don’t delete your evidence! But ACAS will advise you best.
Our polling station is between the chippy and the offy - so vote, grub & bottle of booze to shout at the telly with!