Melinda* had no idea she was being filmed.

She had gone online in search of help to fix a problem with her computer.

Key points: Dozens of Australians secretly filmed using their webcams without their knowledge

Dozens of Australians secretly filmed using their webcams without their knowledge Hacked recordings were posted on Youtube as endorsements for the scam service

Hacked recordings were posted on Youtube as endorsements for the scam service Using an Australian phone number, the scam catches people searching for online support to install tech products

Instead, she wound up being secretly recorded by criminals who seized control of her computer and switched on her webcam.

"I'm very happy with the service I have received today," she says in the video, reading off a script provided by the scammers.

Melinda was unaware that she had been ensnared in a sophisticated "remote-access" scam.

The scammers that targeted Melinda have secretly filmed dozens of Australians in their own homes, luring them in through fake tech support websites.

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Remote-access scammers trick their victims into handing over big money — as well as control of their computers — in return for fake fixes for technical problems that never existed.

The scammers then post the videos to their YouTube page, using them as testimonials to convince future targets that their services are legitimate.

The ABC has tracked down some of the dozens of victims caught up in the scam.

Monash University medical professor Geoff Sussman was fleeced for $1,590 when the scammers accessed his computer.

He managed to get his bank to reverse the transaction, but the experience was deeply frustrating.

"It's very annoying and upsetting," Prof Sussman said.

"There are far too many scammers out there, and even intelligent people can get in their web."

Professor Sussman's troubles began when he went online in search of help downloading Adobe software to a new computer in November 2016.

He found what he thought was an official Adobe tech support page, and called a 1800-number listed on the site.

Geoff Sussman fell victim to the online scam, before eventually recovering his money. ( ABC News: Jeremy Story Carter )

The phone number connected him to an organisation called Macpatchers, whose website has since vanished from the internet.

The Macpatchers tech support operator told him a virus was stopping him installing the software, and asked him to download a program that gave remote access to his computer.

"They're very clever about that. They say, 'look we need to check why this is, and the only way we can do that is to in fact get access to your computer,'" he said.

Geoff Sussman's webcam was accessed without his knowledge. ( Supplied: Youtube )

"Once you give them access to your computer, it's goodnight sweet prince."

Professor Sussman said the operator "did some things" to his computer that made it look like they were removing the viruses.

At the end of the process, they asked him to read out a line of text on his screen confirming he was happy with the service.

They did not tell him they had switched on his webcam and were filming him speak.

"It makes you feel used by these people, that they're violating your privacy," he said.

"I had no idea I was being filmed, and I certainly had no idea they were using me to promote themselves."

Geoff Sussman is disappointed the scam phone number is still being used on the internet. ( ABC News: Jeremy Story Carter )

The video is among 69 secretly recorded clips of Australians posted on Macpatcher's YouTube channel.

The videos capture victims in extremely private settings — their bedrooms, lounge rooms, kitchens and studies.

In some videos, children drift in and out of shot.

One man sits shirtless in front of his computer.

Those who spoke to the ABC were understandably horrified to discover the videos had been posted online.

'Scam-baiter' fights back

The scam was uncovered by self-described scam-baiter David, who seeks out organised criminals online.

He requested his full name not to be used, because he has made enemies out of the criminal organisations he investigates.

"Scam-baiting involves looking for scammers online, calling them up, pretending to be a victim, and then exposing what they do," he said.

"I like to record the process using screen-recording software and then post the videos online."

This page — which comes up when searching for Adobe support — leads people to a scam phone number. ( Supplied )

David called Macpatchers in November last year, and filmed his interaction.

In the video, the Macpatchers operator — who has connected to David's computer — can be seen directing his web browser to the collection of victim videos on YouTube.

"You can check the reviews of Macpatchers, if you have any doubt," the Macpatchers operator says.

David suspects very few of the people in the video would realise they have been scammed.

"You can see that many appear to be genuinely happy with MacPatchers," he said.

"They have handed over hundreds, even thousands of dollars, and not even realised the scammers had done nothing to fix their computer."

The ABC has tried to contact Macpatchers.

David believes one of the most concerning elements of the scam is that Macpatchers used an Australian 1800-number to lure in victims.

He has collected dozens of Australian telephone numbers used by scammers over the past year, and reported the numbers to the telco networks that host them.

"I've noticed even six months later they're still being used by the same scammers," David said.

Scam victim support group IDCare said it had also noticed a spike in Australian telephone numbers being linked to scams.

Telco industry group the Communications Alliance said network providers act promptly to shut down telephone numbers they believe are being used for scams.

"It is extremely difficult to guarantee that an individual or entity that purchases a number will not at some stage misuse it. No such guarantee exists in the world," the group's CEO John Stanton said in a statement.

"Such misuse is extremely rare, but it is virtually impossible to prove ill-intent in advance."

*Name has been changed