They never say: 'I met someone on the internet and I went naked'.Men using social networking and online dating sites are being targeted by fraudsters posing as attractive young women.
A threat is then made to publish the video with false allegations of paedophilia unless money is paid.
French police say they are being told of incidents every day, with most probably going unreported.
"At the moment we are persuaded that there are several blackmail attempts committed every day," says Vincent Lemoine, a specialist in cybercrime in the Gendarmerie's criminal investigations unit.
"Unfortunately, not everyone who finds themselves victims of this crime is coming forward to the police because these blackmail attempts are so intimate." The French reputation management company, Reputation Squad, has received an alarming number of calls from lonely hearts after they were persuaded to reveal too much of themselves online.
She was a very beautiful French-looking girl, very pretty." "She was dressed to begin with and asked whether I would be interested in going further. It was captioned with the victim's name and the false allegation that he was performing a sexual act in front of a young girl.
I asked what that meant and she said she wanted to see my body... French police have received a spate of reports of blackmail attempts fitting a similar description.