The companies include CBS, NBC Universal, News Corporation's Fox Entertainment, MySpace, Walt Disney and Microsoft. The web video site Veoh Networks, which counts Michael Eisner among its investors, is also on board.
Conspicuous by its absence is Google, the parent company of YouTube, which Viacom sued in March for $1 billion over alleged copyright infringement.
Last week, Google announced a new initiative using its technology to filter out copyrighted content on YouTube. The search giant asked media companies to co-operate to help keep their programming off the video-sharing site.