Though still unclear whether NBC Universal and Fox can create a worthy rival to video-sharing site YouTube, what is clear is that they will have to do it without Viacom, which has dropped out of the talks.

Viacom had been in talks with Fox and NBC Universal about forming a video-sharing site that would have exclusive rights to content from the three media conglomerates, Ad Age reports. Viacom has excused itself from the talks, but leaves open the option of licensing its content to a site if one is created.

Representatives from Time Warner and Walt Disney Co. have confirmed that they have no interest in being part of such a venture.

Most media companies have been reluctant to sign licensing deals with YouTube without first making a go at distributing their content from their own sites. Moreover, they likely hope that the threat of a potential rival to YouTube could prompt the site's parent, Google, to pay more for the media companies' content.