Cable networks can't get enough of a soon-to-begin Comcast trial of the On Demand Online video service. It would let cable viewers access shows online for no extra cost beyond the regular subscription fee and some ads.

The trial will bring online lots of movies and TV shows that previously couldn't be legally streamed. Though initially only for PCs, it may eventually spread to mobile phones. Some 5000 test viewers will log onto the Comcast and Fancast sites. The latter already offers free video.

Participating cable networks include A&E, AMC, BBC America, DIY Network, E! Entertainment, Fearnet, Fine Living Network, Food Network, G4, Hallmark Channel, HBO, HDTV, History, IFC, MGM Impact, Starz, Style Network, Sundance Channel, TBS, TNT, and We tv.

Perhaps the biggest eyebrow raiser is that CBS will also participate in the trial, and will no longer send shows to Hulu, which is co-owned by NBC, ABC, and others.