I've dealt with a ring like this when ww.com was still active, a bunch of Romanian women had begun targeting the men on there. In the end I set myself up as a potential victim to see how they went about their business and sure enough, a couple of hours of chatting later the requests for nudity started to roll in.
The girls were all real, I figured out some of their moves and got rid of all of them, it took a while to puzzle out the extent of the whole thing. Likely they made 1000's if not 10's of 1000's of euros before we got wind of it because the victims were extremely reluctant to contact one of the moderators or the authorities.
The simplest advice I can give to anybody that is being propositioned by some girl online is to simply not get undressed in front of your webcam.
It's sad that technology that I had a hand in creating is abused like this, and it really pissed me off that my website was a direct tool for blackmail.
But at least that particular ring got shut down, however it is likely they moved on to other ways of reaching their victims.