Fox and NBC, the American media companies, have given the first demonstration on their jointly owned online video service, which they hope will seize back the intitiative from YouTube's all-powerful site.

Hulu.com, which is still in private testing, will become a platform for distributing professionally produced content on the internet, including new and old television programs as well as some films - all free of charge.

The hope is that users will want to access the two companies' premium content - including 24 and The Simpsons from the Fox stable, and Heroes and The A-Team from NBC - and will be willing to watch adverts for the privilege of doing so.

Fox, which is owned by News Corporation, parent company of Times Online, and NBC, owned by General Electric, will distribute their content on the newly created site, as well on sites owned by five partners in the venture - Microsoft, AOL, MySpace and Comcast.

Two additional content owners - the studios Metro-Goldwyn-Mayer and Sony Pictures - are partners for the venture.

As on YouTube, which is owned by Google, viewers watch the shows inside a web browser. During a 30-minute show they will be shown five or six ads, all from the same company, which also sponsors a 'pre-roll' advertisement.

In a break with other platforms which offer professionally produced content, viewers will be able to cut and paste chunks of video and send them to friends or embed them in their own sites, in such a way that a secondary viewer may not be exposed to any of the ads.

Advertising revenue when a show is streamed is split between the content creator and the distribution site, and varies depending on the type of programme, but the content owner takes the majority, according to executives at Hulu.com.

At launch, the service is aiming to offer ten free films, including Master and Commander and Sideways, which will have commercial breaks.

“You will not find this line-up from top to bottom anywhere else,” Jason Kilar, the chief executive of Hulu, who previously spent nine years at Amazon, said.

“We don’t have to worry about showing TV schedules or letting fans get to know the actors. All we have to worry about is the video," he said.

Media companies have different approaches to distributing their content over the internet. ABC, the US network, is focused on adding its programming to its own website, whereas CBS has built relationships with other video services, such as Joost, which was set up by the founders of Skype.

Analysts said that to develop truly widespread appeal, the venture would have to bring on board more content partners, like Viacom and Disney, but Peter Chernin, president of News Corporation, told the New York Times that while he was "optimistic" that others would join Hulu, "even if nothing else changes, I already think this has more premium video than anywhere else."

James McQuivey, an analyst with Forrester who has seen the service demonstrated, said: "It's not so much a site as a syndication platform they've built. I expect 20 of the videos that are streamed won't be streamed on Hulu itself."

"They've used Flash very creatively, built a lot of features such as sharing tools - and it really gets at what a lot of users of YouTube like, which is being able to share just a bit of a clip - the dramatic bit, say - without having to watch the whole thing."

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