A Melbourne man who was blackmailed by someone he met on an online dating app says he wants to warn others of the risks.

The man, known as James, said he was chatting to a woman online when she demanded money and threatened to release a video of him, which he was unaware she had filmed, if he did not pay.

"I'd been at a work function and I'd been drinking and I suppose the conversation got provocative and I was coaxed on webcam to be in a compromising position," he told 774 ABC Melbourne.

"It then turned into a fairly sophisticated blackmail attempt."

The woman demanded James transfer $800 into a Western Union account, or the footage would be exposed to his friends and workmates.

"Things were said like, 'You don't understand, you're going to wish you were dead once I do this'," he said.

James said he was shown images of personal information from his social media accounts to prove his details were known.

"It was a comprehensive list of all my Facebook friends, a picture of the website of my employer, including email addresses of my colleagues, my LinkedIn page, photos of my friends, my personal website," he said.

However, when James tried to seek help from Victoria Police, he said he was told to file an online report with the Australian Cybercrime Online Reporting Network (ACORN).

"I said [to police], 'This seems quite a lot more urgent than that'," he said.

"There's a person yelling at me, threatening, saying 'If you don't respond to me and tell me you're doing what I'm doing, things are going to get sticky for you'."

James said he tried to block the blackmailer and deactivate his social media accounts, however the video was sent to several people.

In a similar case, Melbourne man, John, said a woman he met online also filmed him without his knowledge and demanded $500 to not release it.

He said like James, he was sent images of his Facebook account showing his children and friends, with claims his loved ones would be sent the video unless he sent money.

John said he contacted Victoria Police who also referred him to ACORN.

He said he submitted an online form in September and received an auto-reply, but was only contacted by phone about the matter four months later.

"This was the worst night of my life," he said.

"There aren't many people you can speak to about this, it's utterly humiliating."

The ABC contacted Victoria Police, who said they were unable to issue a response today but would follow up the reports.