Is the issue with person A videoing person B that a) B doesn't know they're being filmed b) B knows it and doesn't like it c) something else. I think likely b) so now we get to is whether A's conduct legal. If A is located in a public place, e.g., a public sidewalk, they can legally film whatever they can see. They can do this using a phone, Meta glasses, a camera on a tripod, etc. For example, A could stand on the sidewalk in front of your your house and legally film you through an open window. Kinda creepy but not illegal.