Every single barn has an annoying/irritating/fussy/aggressive/loudmouth/etc. person (or persons!) at it. So long as they are not actively harming you or preventing you from riding, just go about your business!
I make a point of being a friendly brick wall to these sorts. Smile, say hello, and then keep motoring on my way. No stopping, no small talk, just keep on moving and doing my own thing. There are plenty of people who I will stop and chat to, and they make my barn life that much brighter, but the one or two who seem to spell trouble? There’s just no need. We’re all at the barn to ride, so just get busy riding.
The recording thing is very odd - but really - so long as you are not beating your horse black and blue, who cares? Sure, someone can edit a video to show the worst moments of a ride compiled into a montage, but it would be fairly obvious to anyone viewing it - and really, who is the audience for this? Unless this is 1995 and you are Nicole Uphoff, probably no one is going to particularly care about watching you ride. If someone on one of the local horsey FB groups I am just started posting tons of edited together clips of another rider looking bad all it would serve to accomplish would be to wave a REAL big red flag over the head of whoever is posting that nonsense.
If someone starts recording you and you don’t want to be recorded, ride over and tell them to stop. If they wont stop, stand still for a few minutes and don’t give them anything to film. If they persist beyond that, that is quite odd and definitely crosses a line into inappropriate behaviour - though really, what they would do with those videos is beyond me.
If this is paranoia about maybebeing recorded? Erm, perhaps think more about what on earth that would possibly accomplish by doing that - aside from annoying you, which is totally in your control, and if you just continue breezily riding along not caring about it it will probably swiftly take all the fun out of it.