The person filming at the party isn’t thinking about your future. You have to.

Whoever is holding the phone is solving for the next ten minutes. They want the reaction, the laugh, the post, and none of that involves what the clip does to you in five years, because that is not a cost they will ever pay. This is not usually malice. Your future is simply not in the frame.

When a camera comes out, decide immediately whether you want to be in it, and step out of shot if not. Ask people not to post things with you in them, early and without making it a confrontation. Be the person who checks before posting others.