What can only be described as a "gaggle" of teenage girls spent their weekend at a convention centre in southern California, standing patiently in a queue which stretched roughly a hundred yards and, depending on the time of day, took anywhere from two to four hours to negotiate.
They were queing to meet a 21-year-old Englishman called Charlie McDonnell, who sat flanked by security guards. Every couple of minutes, another excited fan was beckoned forward to exchange polite conversation and perhaps acquire an item of autographed memorabilia.
Charlie, who resembles Justin Bieber's slightly geeky elder brother, inspires extraordinary devotion. His public travelled from far and wide to attend his celebrity meet-and-greet, and would occasionally emit a chorus of eardrum-bursting shrieks for watching TV camera crews.
"He's just a beautiful person. I don't know what else to say," explained 15-year-old Victoria Jefferson, whose parents spent four days driving her from Tampa, Florida, to the event in Anaheim. "Am I in love with Charlie? Over the two or three years I've been a fan, it's slowly turned into something like that."
Behind her stood 17-year-old Dana Biersteker and her mother, Marca. "Charlie is cute, of course, and quirky-funny," she said. "All the girls at school are into him." Asked what she was going to say upon finally meeting her idol, Biersteker turned crimson. "My gosh; I don't know. Probably something normal, like 'hi!'."
To the casual observer, McDonnell is every inch the teen idol. Yet his apparent fame, which allowed him to offload crate after crate of $10 posters and $20 T-shirts, did not come the old-fashioned way. He has never sung in a boy band, acted in a soap opera or even, heaven forbid, set foot on a Hollywood red carpet.
Instead, Mr McDonnell, who grew up in Bath and is better known as "Real Life Charlie," is one of the biggest stars of YouTube. He earns a reputed six-figure income creating short, charming "vlogs" (video blogs) about his daily existence, which are circulated to 1.5 million "subscribers" and have, at the last count, been watched almost 250 million times.
From Friday to Sunday, he was among the most popular delegates at the third annual VidCon, a gathering of online film-makers, viral video stars, industry power-brokers, and roughly 6,000 fans who, in the jargon of social networking, click "like" on the content that Mr McDonnell and people like him upload.
The sold-out event bears witness to the frenzied manner in which the internet has upended traditional rules of celebrity, turning YouTube, which was founded seven years ago and now gets more than four billion views each day, into what is potentially the most powerful organisation in the history of entertainment.
It also illustrates how a medium famed for blurry footage of cats on skateboards is morphing into an outlet for professional programming. There are now more than a thousand YouTube "partners" earning in excess of $100,000 (£64,000) a year from the website. Their overall revenue has doubled in each of the past four years.
"It's the new rock and roll," says British entrepreneur Justin Gayner, the founder of ChannelFlip, one of the leading online TV companies, which was recently acquired by Rupert Murdoch's News Corp. "These guys are genuine stars. We look after the fan-mail for four or five of them. They get hundreds of letters a day, containing everything from underwear to chocolate bars. This week, we had post from New Zealand, Japan and India."
VidCon began in 2008 as an informal gathering of YouTube enthusiasts in a New York park. In 2010, it morphed into a traditional conference, attracting 1,000 delegates to an Anaheim hotel. Last year, 3,600 came. This year, that number almost doubled, drawing representatives of Hollywood studios, TV networks and talent agencies.
"The cycle is very similar to what we saw at the start of MTV," says Fred Seibert, an influential TV and film producer who helped launch music television in the 1980s and has been investing in online video since 2005. "At first, people were asking, 'why would anyone watch this?' Then they'd ask 'why isn't it making any money?' After that, they begun saying 'how can we get in on this thing?' That's where we are with internet video."
Watching the stars of YouTube collide is a surreal experience. Depending on your point of view, the cavernous, noisy conference hall – a stone's throw from Disneyland and decorated with luminous signs issuing such proclamations as "can I haz a retweet?" and "cuz it's a meme ;-)" – represents either a forward-thinking vision of our cultural future, or a sobering indictment of the decline of modern civilisation.
Crowds of teenagers, in a uniform of skinny jeans and elaborate orthodontistry, queue to shake hands with such online superstars as Rebecca Black, the teenager behind the viral pop video "Friday", and Justin Stewart, a 19-year-old from Colorado who earns a living making videos of himself falling over in public. Loud music, flashing plasma screens and grown men with pink hair and body piercings compete for the attention of passers-by. In quieter conference rooms, aspiring YouTubers attend panel discussions on such subjects as "So you want to be a vlogger... Now what?"
Soaking up the carnival atmosphere is a smattering of British talent, including Louie Cole, a dreadlocked 20-something whose oeuvre revolves around eating live animals and road-kill, and Sam Pepper, a former Big Brother contestant who specialises in comic monologues and hidden-camera pranks. "When I tell people I'm doing YouTube, a lot of them ask if I hope to be on TV again," he says. "My reply is always 'why would I want to be on TV?' Online film is incredibly rewarding. And when you tell people the money you can make, they're shocked."
YouTube, which is owned by Google, keeps the exact details of its financial model secret. But most content providers say that, under ad-sharing arrangements with the site, they earn between $1 and $3 for every 1,000 people who view their clips, along with additional revenue from product placement and sponsorship.
For most big YouTube stars who can draw around 5 million views a month, that equates to low six-figure incomes. But behind the scenes, big players are starting to properly cash-in. Simon Tofield, a British animator whose "Simon's Cat" cartoons have been watched 260 million times, recently signed a syndication deal with Disney. Freddie Wong, a portly special effects guru who was VidCon's biggest star – his films boast 650 million views and 3 million subscribers – recently had his net worth estimated at $6m.
And to victors of this brave new medium, the wider spoils. "Are girls throwing themselves at me at VidCon? Hell yes!" said Tom Milsom, a London-based YouTube musician. "It's great, in every way, apart from when they turn out to be 14. In the old days, Andy Warhol said that everyone's famous for a few minutes. Nowadays, thanks to YouTube, everyone's famous to a few people, and mine seem to all be here. It's a weird sort of micro-celebrity, and I'm loving it."