Joost opens online video service

Joost, the on-demand online video service backed by the founders of Skype, has launched commercially.

The internet television service boasts more than 150 content channels - from cartoons to music videos and films.

Services like Joost may change the way viewers consume media and revolutionise the business model of broadcasters.

Until now Joost could be watched by just a few thousand testers. These will now be given an unlimited number of invitations to give to new users.

The service provides video streams in broadcast quality, and is distributed using peer-to-peer technology.

The founders of Joost - Niklas Zennstroem and Janus Friis - are also the team behind the hugely successful internet telephony service Skype.

Blue-chip partners

Users of Joost must download a small application that allows them to watch the video streams on demand.

Joost is still building up the number of content channels on offer

The services delivers full-screen high quality video, a huge advance on the small size of film clips offered on websites such as YouTube or the BBC.

Films on Joost are interrupted by adverts from the 32 blue-chip companies that are the company's launch partners, among them Coca Cola, Hewlett Packard, Intel and Nike.

During the test phase, Joost channels were mainly suited for a young and male audience, heavy on music, sport and light entertainment.

In recent weeks, however, Joost has struck a series of content deals, among them US media giant Viacom. Later this month, CNN will start delivering news on the service, while Sony will offer classic programmes from the 1970s to the 1990s.

'Viable business'

Joost will not rely on user-generated content, although it will allow small production companies to become broadcasters in their own right, Mr Zennstroem told the BBC earlier this year.

He predicts that television sets will "become more and more computerised and internet enabled," which would allow Joost's advertisers to make the all-important leap from the study to the living room.

Mr Friis said Joost had managed to become a "viable business versus just a cool technology" by being able to bring together advertisers, content owners and viewers.

Joost users, however, must be aware of the heavy load the service will put on their broadband connection.

If the deal with their broadband provider has usage limits, they could quickly find themselves paying extra.