Video released on YouTube shows grainy footage of a flying object which appears to rise and hover in the sky.
Conspiracy theorists believe the video to have been recorded in the late Eighties or early Nineties.
The “UFO” appears to emit a light as it seems to move from side to side.
Secureteam10 is behind the release and its producer Tyler Glockner claims in the video it is some of the most compelling UFO evidence out there.
He said in a video about the clip: “It is alleged to have been recorded back in mid to early 1990s or possible even late 1980s.
“It is said to be of an alien vehicle being tested over the very secretive base known as Area 51.”
But, sceptical ufologist Scott Brando, who runs hoax busting website ufoofinterest.org said the video was not even recorded at Area 51, but another top-secret USAF base in Nevada.
Mr Brando provided the same footage which was said to have been recorded at the Nellis Air Force base in Las Vegas on May 30 1995.
He regularly highlights Secureteam10 for misleading its more than 750,000 subscribers.
He, and a number of UFO hoax busters claim to have exposed its use of CGI footage and misrepresentation, and the channel appears on a numb roy UFO website blacklists.
Mr Glockner denies being a deliberate hoaxer, and claims his research is genuine.
He added in his new video: “It’s one of the mysterious pieces in UFOlogy – a hidden gem.”
The heavily guarded Area 51, deep in the Nevada desert, is at the centre of many alien-related conspiracy theories, but so is the Nellis base.
It is claimed that alien flying saucers have crashed on Earth, such as the alleged 1947 Roswell incident, and that the wreckage and even corpses have been taken to both bases to be analysed away from public view.
One theory suggests that USAF scientists have tried to back engineer the alien technology to create their own top-secret spy craft capable of travelling into space.
The conspiracy theories have been fuelled by the fart the US Government did not acknowledge Area 51 existed until 2013.
But, it is accepted that the USAF does secretly test new aircraft there, with the U-2 spy plane, SR-71 Blackbird, and the F-117A Nighthawk stealth fighter all developed there.
Nigel Watson, author of the UFO Investigations Manual, said: “Area 51 has always been a magnet for those who believe the US Government knows a lot more about UFOs than they are prepared to reveal to the public.
“People like the late Boyd Bushman, a senior scientist who worked for Lockheed Martin, have declared that Area 51 is a base where extraterrestrial spacecraft and technology is stored and examined.”
Mr Brando said he believes the 1995 footage from the Nellis base is a standard military craft or other operation taking place, and that there is no evidence to connect it to alien technology.
Mr Brando told Express.co.uk: “It’s old footage published in the 1990’s by several UFO magazines with VHS.
“We don’t know if the audio of the video is original or counterfeit.
“These kinds of movies were deliberately cut and packed for the mentioned magazines.”