I can't see the similarity there at all - a video is a lasting record that could also be identifying, plus it's somebody doing something they've been asked not to do or that they know (from advertising) isn't on offer, plus covert filming is illegal? I'd liken this more to leaving a used tampon in the bathroom bin (or a poo in the toilet even - I don't use tampons and I do flush toilets ) and somebody deciding to fish either of them out and make merry in whatever way they saw fit.
Would I think it was grim - yes. Would I be precious because it was my tampon or poo? Nope. Unless I'm missing something and men are weird about semen in particular as a waste product? If so, they must have a terrible time when they have a wank .
I think your analogy is probably better - but yes I'd still object mightily to someone taking my poo, pee, snot, sweat or blood and using it for their own gratification. Because it's not just a "thing" - it's something biological, that was created by and came out of me. And if it was being used for someone else's sexual gratification
without my consent then I would feel violated.
I'm happy to sell used knickers, I'm happy to pee on someone, but those are acts to which I've agreed.
Anyone helping themselves to my poop must have had a nasal bypass, mind