Thousands of unsettling videos have been uploaded to YouTube over the past year. Nobody knows what they mean or who’s behind them – but a band of intrigued Redditors, obsessed with the mystery, are trying to find out.

Update: A few hours after this article was published, the YouTube channel was suspended without explanation.

“I didn’t get to bed till about two last night,” says Reddit user its_safer_indoors on the phone from Melbourne, Australia. “Work was not fun today,” he adds with a laugh.

He’s not the only one who’s lost a little sleep over “Unfavorable Semicircle” – a YouTube channel that has published tens of thousands of inexplicably weird videos since April last year. Shawn Sweep, a university student in Maryland, USA, has been staying up late, too.

“I’ve been reviewing stuff, looking at things other Redditors have found and trying to connect the dots,” he says.

This isn’t the first time a mystery like this has gripped users of YouTube and Reddit. Famously, a series of videos called “Webdriver Torso”– featuring random coloured shapes and high-pitched tones – prompted all kinds of conspiracy theories. Were they secret messages intended for spies? Or abstract architectural plans? In the end, the answer was simple – it was Google’s own method of testing content delivery on YouTube.

In the case of Unfavorable Semicircle, however, the videos aren’t so neat. The visuals are blurry, often featuring dark tones and with “constellations” of dots in seemingly random arrangements. The audio, though, is what has spooked most viewers. In some of the videos, a male voice, heavily muffled, is heard reciting assorted letters or numbers. Most of the clips last four or five seconds, but there are a couple that are much longer – including Lock and Delock.

They just creep me out – Shawn Sweep

Lock, in particular, is notable for the intensity of flashing colours and unnerving, warped audio which continues for over 27 minutes.

Sweep says one of his biggest fears is strange noises. “They just creep me out,” he says. But although he found the Unfavorable Semicircle clips disturbing at first, he now feels somewhat “desensitised” to them because he’s watched so many.

The Webdriver Torso videos perplexed internet users before Google explained what they were

“The main reason I’m still in this entire thing is because of the two videos, Lock and Delock – they’re so weird,” he comments. “In Delock, at one minute 26 seconds it sounds like a man whispering, but I don’t know if that is my imagination or if that is actually what I’m hearing. After that you hear kids singing.”

User its_safer_indoors works professionally with audio visual technology and he too has been fascinated by Delock. He’s experimented with slowing down and speeding up the clip’s audio to see if anything more can be revealed, but so far he’s not turned up much.

However, he has set up a website dedicated to solving the mystery. This has involved compiling a database of videos to make them more easily searchable than via YouTube itself. And, a handful of Redditors have offered to help transcribe any verbal content that can be heard in the hope that analysing the data could unearth some meaningful patterns.

At present, there’s no clarity at all on what’s going on – but that hasn’t stopped people wondering. The theories range from Unfavorable Semicircle being another test channel to the “work of a disturbed mind” – and even a kind of numbers station. Numbers stations make seemingly nonsensical radio broadcasts that are actually coded messages and have been used since World War One. Efforts to “decode” the videos have ranged from attempts at analysing the dot constellations to questioning the use of the Sagittarius symbol in video titles. All the while, more keep getting uploaded – at a rate of about two every minute.

Neither Sweep nor its_safer_indoors have pinned down a theory that satisfies them completely. Sweep says he’s leaning towards the videos being the output of a bot, perhaps performing some strange kind of test, whereas its_safer_indoors thinks they could form an “elaborate puzzle”. But neither can be sure.

When puzzles come onto the web they are normally announced in some way, albeit subtly sometimes – Alan Woodward, University of Surrey

Security expert Alan Woodward at the University of Surrey doubts it’s a numbers station. “Too complex,” he says. He also questions the likelihood of the clips being a puzzle, perhaps – as one Redditor suggested – acting as a recruitment tool for Google.

“When puzzles come onto the web they are normally announced in some way, albeit subtly sometimes,” notes Woodward.

He suspects another test but admits it’s just not clear what’s going on – and points out that someone certainly seems to have put a lot of effort into creating the videos.

“It's not unknown for government agencies to plant complete red herrings that have absolutely no meaning but soak up an inordinate amount of time from the opposition,” he says as an afterthought. “When it's done on the internet, the curious can become unintended ‘victims’ and it's they who waste their time.”

When asked, Google was not able to provide a comment on the channel so the mystery, for now, remains open.

It’s good to work with a bunch of people all trying to achieve a common goal – Reddit user its_safer_indoors

“I want to know what it is,” says Sweep. He doesn’t feel like anything sinister is going on but he, like many others now intrigued, wants to see it solved.

“Everyone likes a good mystery,” adds its_safer_outdoors. He, for one, admits something of an obsession over the clips: “I haven’t really done much else for the last couple of days.”

Whatever Unfavorable Semicircle is about, and whoever is behind it, there’s no denying that the videos are unsettling. They’re overly enigmatic, seemingly begging for someone to explain what they’re for. These kinds of riddles are perfect for the age of the web – an age in which information is so abundant and, often, formulaic. Here instead is something mind-blowingly weird. It would seem neglectful to simply let the puzzle lie, so minds from across the globe combine to try and work it out.

As with any mystery, there is no guarantee of a solution. But the chance that one might be found is enough to keep plenty of people interested. And so, they stay up late at night. They shoot theories back and forth. Maybe, with a bit of luck, someone just might crack it.

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