There have been many films made of sexual murders in this country, in fact many of these films have been used to convict murderers.
Charles Ng and his partner Leonard Lake filmed most of their female victims; these films were part of the prosecutions case against Ng. Lake committed suicide before he could be prosecuted. To this day nobody knows how many people these two killed together or in Lakes case, individually.
David Parker Ray with his girlfriend and partner Cindy Hendy, kidnapped women to violently torture and rape them - they taped the victims. Ray died his first day in prison and is considered the prime suspect in the murder of dozens of missing women in New Mexico. Hendy currently sits in prison and while she’s never admitted to taking part in any murders, she says Ray told her about many he had committed.
Paul Bernado and his wife Karla Homolka, kidnapped teenage girls, raped, tortured and killed them, almost all on were on tape. Bernado is serving a life sentence while his now ex-wife was released after serving 12 years. Karla made a deal with prosecutors to testify against her husband before the tapes were found. She assisted in the murders, including the rape and murder of her own sister. This case caused a huge controversy in Canada.
These are only a few examples of sadistic sexual serial killers who’ve taped their victims, there have been many others.
The Urban Legend is based on a supposed international group who kidnaps women to be tortured, raped and eventually murdered on tape and then places those tapes up for sale for rich men to buy. There has never been some underground group found that does this, hence the urban legend.
My point was really exactly what you said in your last paragraph. I'm not convinced that there is an international trade in these films. Those that exist seem to be made for the personal use of the murderer(s).
The article about Natalie Holloway mentioned "the snuff trade" and it is that "for-profit" aspect of this terrible practice that I believe to be an urban legend.