“Suddenly they had this panoramic view of Hong Kong, and it awed them that they’d gone all the way over to Asia. So they made me their featured video in the first week,” he says.

His most popular Periscope came after it was reported Alibaba’s Jack Ma may have bought a house on Barker Road, on The Peak, which Leyden walks past every day.

“I said, ‘This is a house that cost US$193 million, and I had 400 or 500 viewers in the first minute,” says Leyden, who scopes daily on his informative walkabouts, visiting everything from second world war sites to shopping malls.

Surprisingly, visits to McDonald’s are popular, Leyden says. “I order those unique Hong Kong items like the Prosperity Burger and the Shogun Burger, and have a taste test, and they go bananas: ‘What does it taste like? Is it good?’”

Periscope has grown rapidly to become the most popular live-streaming app, with more than 10 million accounts in the first four months. At the end of August, more than 40 years’ worth of video was being watched daily, a local Twitter spokeswoman says. The company does not give breakdowns by area.

Followers tap on the screen to send hearts, or post comments, which Periscopers answer verbally. Scopes can also be replayed for 24 hours before they auto-delete. A map shows where users are streaming from anywhere in the world.

Leyden says his only problem with the app is bandwidth; he scopes a few times daily, which eats up one gigabyte. Each broadcast minute uses 1 per cent of battery life.

The majority of his followers are in the US, he says, including former Hongkongers who ask him to stream from places they remember, especially markets and bakeries. A popular request is a walk to a pedestrian crossing. “When they hear that clicking sound, they’re like, ‘I’m almost crying. I miss that sound’.”

He recently met two Australian tourists who had followed his scopes, and took them to The Peak.

Entrepreneur John Ho, whose handle is @JohnHo and who has close to 7,000 followers, has also been promoting Hong Kong. The operators of the Ngong Ping 360 cable car and ICC’s Sky100 viewing deck even gave him free access to scope.

Ho’s first encounter with Periscope was watching the boxing match between Floyd Mayweather and Manny Pacquiao in May. “My friend downloaded the app and we watched it through that. Someone was just scoping the TV.

“Later I started using it, and as soon as I pressed the red broadcast button there were people coming in,” says Ho, who estimates 70 per cent of his viewers are in North America.

“I focus more on the cultural aspects of Hong Kong, anything related to traditions, interesting landmarks. What most people find fascinating is when I just walk the streets. When they see the tall buildings, the double-deckers, swarms of people crossing the road, visually that’s just very captivating.”

Ho also uses his scopes to plug businesses he is involved in when followers ask him about his job. “I’ve actually acquired a couple of business partners online,” he says.

Briton Jonathan Morris, aka @JonathanJK, whose next milestone is 6,000 followers, is monetising Periscope through private scopes. The English teacher and journalist says only the first 100 or so viewers are able to comment. Private scopes allow loyal followers, who donate a minimum of US$1, more opportunity to chat. He also raised HK$2,000 through a GoFundMe campaign to buy a microphone.

Asked in a scoped interview if they would be more inclined to visit Hong Kong after seeing his scopes, many follows expressed a keen interest. Asked why they follow Morris, viewers cite his humour, irreverence, “vibrant language” and interesting content.

Followers particularly like his morning coffee chats from his Kowloon flat, which overlooks a food market. One of his most popular scopes was a visit to the Sha Tau Kok restricted area, where viewers were interested in learning about its political history. He is also visiting the city’s remaining colonial-era post boxes (whose colonial emblems Hongkong Post has proposed covering up).

He says he originally wanted to document Hong Kong photographically, until Periscope came along, and wants to produce a book.

“I’ve always envisioned it as a multimedia type of book; articles, photos, videos, which is perfect for Periscope. The app is augmenting what I wanted to do here,” he says, adding he saves scopes on his camera roll and downloads them on YouTube.

“I knew about the power of photography, and I’ve just applied what I learned at journalism school straight to video: the democratic power of holding a phone that is basically a TV channel.”

Engagement with followers is key to being a successful scoper, he says, but this can also encourage trolls.

“I love them. I try to heckle them down, and I’ve got the power to block them. But I’m a guy; I can play with this. A woman is more vulnerable.”

Chloe Chan, who scopes as @petitecherrycom and has about 2,000 followers, is often trolled and says it’s getting worse. “Basically it’s males commenting on my looks. They tell me I’m cute, beautiful, etc, which are just mildly offensive but not adding value to my scope. Then there’s the downright offensive who ask you to show your legs or boobs. I immediately block these people.”

The Canadian-Chinese entrepreneur shows followers the quirky side of Hong Kong. She recently scoped a Japanese vending machine with sushi girl and burger girl toys. For one scope, she was asked to stream from Dim Sum Icon restaurant in Tsim Sha Tsui. One of the dishes was a bun shaped like Japanese egg-yolk cartoon character Gudetama, which has buttocks. Digging in, she discovered a chocolate goo inside.

Chan gets many followers who know little about Hong Kong and ask questions such as: “Is there an internet firewall? Do you eat cats and dogs?”

She used to scope a few times a week but has been busy in the run-up to the festive season with her e-commerce websites, including Petite Cherry Intimates, which sells Japanese lingerie.

Chan also uses Periscope to promote her business. “I scope about the process of design, or visit the factory and show a woman sewing. Maintaining authenticity is more important than just showing the products,” she says.

RTHK Radio 3 host Steve James scopes as @steveonradio3 and has more than 800 followers. He uses Periscope to give another dimension to his show. He often gets viewers from the US, who are surprised to find a Western DJ working in Asia.

James says he has also been contacted by an audio entrepreneur and engineers, and even a Scotsman who is promoting his son’s music.

“I didn’t think I could do what the other guys are doing. I’m too busy,” he says. “It occurred to me that all I can offer is the radio show. The downside is, it’s just a radio show. It’s way too long a cast [three hours] and on at a rubbish time of day for America.” The show finishes at 6pm.

“Engagement is very important. Sometimes I’ll stick an album cover of compilations in front of the camera and ask them to choose. I’m scared of requests, though, because the chances are I haven’t got them.”

Live streaming is something James thinks the tourism board “should be all over”, and has seen it used for promotional events, including at the Harbour City shopping mall. It’s becoming a hot topic, with other platforms offering the medium, including Meerkat, YouTube Live and now Facebook Live.

Leyden says streaming – as when Hong Kong scopers “blitzed” Lantau last month – may be too unconventional for official tourism promotion. Nevertheless, it offers outsiders unique and honest perspectives from ordinary residents.

“You can watch 1,000 videos prepared by the tourism agency and not even have a flicker of interest in Hong Kong, even though they’re professionally done and feature movie stars,” he says. “But when you’re raw and walking around, you can show them the busy streets, tell them how much your noodles cost.”