Joost is the brainchild of Kazaa and Skype inventors Janus Friis and Niklas Zennström. It is a free online TV service that is still in beta and has yet to complete its sign-up of content providers.
Viacom was previously reported to be talking to Google-owned YouTube about allowing some of its content to appear on the site, but earlier this month it demanded that YouTube take down 100,000 clips of its copyrighted content.
The breakdown of the CBS deal and the willingness of Viacom to sign with Joost could be a sign that content owners are deserting the user-generated buzz of the web 2.0 hero YouTube in favour of the more controlled Joost.
Joost's is a closed network which will provide only selected, pre-approved material, much like existing television, only without the schedules. Users download Joost software and can choose to watch streamed television or films whenever they like, choosing from the entire catalogue of material and watching adverts which will pay for the service.
YouTube, on the other hand, is designed to be open, and to accept videos from anyone who posts them there. Its success has been built on short clips of shocking or funny incidents caught on camera as well as snippets of TV or film material posted without copyright owners' permission.
The Viacom-Joost deal will give Joost users access to much, but not all, of Viacom's content, including television from MTV, Comedy Central and film studio Paramount.
Joost is a peer-to-peer (P2P) network, meaning that material is hosted and shared by all users, not just by a central server. Though peer-to-peer technology is currently associated with unauthorised file sharing, Joost's will be a closed network.
While YouTube's service provides video through a small screen within a webpage, Joost, which used to be known as The Venice Project, delivers video on a full screen with its own interface designed around channels of similar content.
Joost beta test mode and no official launch date has been named. The results of the Viacom deal will only go live at full launch, which is expected later this year.