pippa68 - I feel branding them all as 'mentally ill' is clouding things. Yes, there must be something wrong with them - 'normal' people (for want of a better word) do not get turned on by pictures of naked children, and as for signing up to see live video links of poor terrified kids being systematically abused and raped by grown-ups, the mind boggles.
However, I fear a sympathetic approach will have them laughing all the way to the psychiatrist. This isn't mental illness in the sense of people who wander down the road talking to themselves and swearing at pigeons. Many of these people are outwardly 'normal' (there's that horribly insensitive word again) - perfectly capable of seeming charming to outsiders, holding down respectable jobs as lawyers, bankers, (heaven forbid) teachers and so on. Many of them are fiendishly clever in hiding their little 'hobby' from friends and loved ones. They know full well what they are doing, but don't care about the effects. We need to accept that some people are just evil.
One big worry I have is that they are not only creating victims, they are also potentially creating future paedophiles. Many school bullies have been victims of bullying themselves, how many of today's paedophile victims are going to grow up thinking this is an acceptable way to behave towards children? I'm not making an excuse for them - after all, many people go through some kind of childhood trauma and come out of it as well-rounded adults, but if anyone needs help, it's the victims. Rescuing the kids in that ring was great, but they now need as much counselling and support as they can get.