I feel for you situation, and I'm sorry you and those around you have had such issues.
Indeed your mention of the uniform, along with it being shaky cell phone imagery, would cause me to moderate such an upload if it was brought to my attention - I would stop it from public availability and notify the uploader that they could respond with proof of age and rights if they'd like to prove the claim wrong. (99% of the time that does not happen)
Sadly, I can't say that you are 100% right on the uniform thing - especially in certain places, copying such uniforms or acquiring exact copies and using such for videos is kind of common.
Fake-revenge porn is actually a thing, and has been for a long time. There are some slick web sites out there that try to make it look like it's 'stolen / hidden video' of girls next door - but it's actually now budget / average girls selling vids cheap and it's packaged in a way to make it seem real.
With that being said, there are also some 'parasite sites' that take imagery of people out of context and use it for sexualized viewing without the person's consent - and I abhor that.
There are also people who do revenge porn, and blackmail porn I would say it's likely even more prevalent. That kind of thing really ticks me off too.
I don't know a lot about xhams, but I'm pretty sure they play with different jurisdictions and rules that pornhub and some others - so I'm not going to comment on the way they do things.
I will mention that I do get quite a few 'takedown requests' from cam models, so many do not understand how affiliate promos work, partner promotion agreements, APIs and such.. sometimes they also push dmca complaints to google and others in an attempt to rush a pic removal... I have also seen some people working with these models who get 'creative' in their removal requests, putting in emails to me (and likely to our hosting companies, google, etc) - that "not only are these pics not authorized for use, but they we're under 17 when they were made" -
As to where I am sure this works to speed up the deletion process for some, it's a shitty thing to do for many reasons - but it is done a fair amount. With so many of these fake take down notices, it's not easy for a moderating team to sort out what is legit and what is not.
It's obvious to me that sometimes this is done by a new boyfriend / husband who is trying to remove past history of their lover's porn work.
It also clogs up our system of support emails. So there is much more to these issues than most people who would file a legit request would know.
It's not always easy to determine these things.