By Darren Waters
Technology editor, BBC News website
YouTube may have started life as an online repository for wacky home videos but has quickly grown up to become a professional media platform that has transformed the way global broadcasters look at content and audiences.
YouTube founders Steve Chen and Chad Hurley tell the BBC about the video site's new direction.
UK Prime Minister Tony Blair has more time on his hands now that his premiership is ending, but it was still a surprise to see him endorsing YouTube.
In a short clip recorded especially for a press event, he described the video service as a "shining example of innovation".
He said he had been shocked to learn that he was the first world leader to have his own YouTube channel.
But it is clear that everyone from politicians, global media firms, teenagers in bedrooms to self-publicists has learned the power of YouTube.
Given its impact, it may raise a few eyebrows to learn that co-founder Steve Chen says the firm is committed to a "engagement, not interruption model".
Quite simply, YouTube has not merely interrupted the broadcasting model of the 21st Century, it has torn it to shreds and shaped it anew.
Everyday hundreds of millions of videos are watched via YouTube. Every minute of every day, six hours of fresh video are uploaded.
Our goal is to have YouTube on every screen - to take it from the PC to the living room and the mobile phone."
Steve Chen, YouTube co-founder
According to analysts Ellacoya Networks, YouTube videos account for 10% of all traffic on the internet and some experts fear that its popularity threatens the very foundations of the internet itself.
In one day, YouTube sends the data equivalent of 75 billion e-mails, according to network specialists Cisco systems.
YouTube has re-defined how the world thinks of media creation, consumption and distribution and with more than half of the traffic the site now receives originating outside the US, it is truly a global media player.
"We want to entertain, inform and empower the world through video," said co-founder Chad Hurley in an interview with BBC News.
When it started YouTube was a quick and easy method of sharing home made video with friends, but exploded as users realised they could also post short clips from TV shows, movies and music videos.
"YouTube is about more than entertainment, it's about education, inspiring people and taking action," said Mr Hurley.
He said: "It's truly about people contributing original content and sharing expertise and talent with the rest of the world."
Tony Blair is among those to have embraced YouTube
Fellow founder Steve Chen told BBC News: "If you go to the site today, there's a great mix of professionally produced content, next to user generated content."
And that is a sign of how YouTube has matured - the firm has signed deals with more than 1,000 partners, and more than 150 deals with content providers in Europe since March.
The founders of YouTube may appear to be Generation X slackers - Steve Chen is 29 and Chad Hurley is 30 - but they speak the language of 21st Century media executives.
Mr Chen said: "YouTube is a platform, a distribution vehicle.
"We don't produce content but we give content creators the ability to reach an audience perhaps they weren't able to reach before - perhaps they didn't have distribution or syndication vehicles to reach the audience.
"We have upload mechanisms to mass upload files and tools to create branded channels."
Rather than bury its head in the sand, mainstream media has decided to embrace YouTube.
"YouTube changes the way media is consumed and messages are delivered," said Mr Hurley.
He added: "The partnerships are just providing more great content for the audience with new opportunities for media companies to get in front of people wherever they are spending time.
"We are about all types of content on our site. What's different is that we haven't been making the decision about what is popular - the community does that."
But as quickly as the firm grows, legal cases claiming copyright infringement are landing on its doorstep.
But the founders said they had not been distracted by the legal action.
Mr Hurley said: "It's not a distraction because from day one we have always obeyed the law and been aggressively working on technologies and creating policies and partnerships to create options."
And for any media executives who still think that YouTube and online distribution is a passing fad, the YouTube creators were clear about the future.
Mr Hurley said: "There are exciting new opportunities to distribute content.
"We have been fortunate to create a popular site - but we won't be the last."
Mr Chen added: "Our goal is to have YouTube on every screen - to take it from the PC to the living room and the mobile phone."