This is interesting as part of Comcast’s on-going effort to beef up its on-demand platform. It’s a potential haven for advertisers who like the fact that fast forwarding is disabled, and they may discover opportunities to target sales pitches to specific viewers.

The No. 1 cable company says today that TV subscribers with one of its X1 set top boxes now can watch brief video clips on demand from more than 30 major cable channels. The content was previously just available online to its Xfinity broadband customers.

“Initially, available content will focus on news, sports and current events like segment clips from NBC’s Today Show and Fox Sports Live,” Comcast Cable Video Services General Manager Matt Strauss says in a blog post. The catalog “will continue to expand as programmers look to super-serve their viewers by integrating even more extras, bonus, and complimentary series.”

The ad-supported material comes from NBCUniversal as well as A+E Networks, AMC Networks, Discovery, Disney, Fox, and Scripps Networks. It’s available through Xfinity on Demand under the “Web” tab. The company has more than 10 million X1 boxes in the field.

“This is really just the beginning,” says Scripps Networks EVP Henry Ahn. “X1 gives us the opportunity to seamlessly integrate new categories of content all in one place. We look forward to bringing even more content and experiences to the X1 platform as we create new partnerships and expand existing ones.”

Channels contributing content include A&E, ABC News, AMC, American Heroes, Animal Planet, BBC America, Big Ten Networks, CNBC, Cooking Channel, Destination America, Discovery, Discovery Life, DIY, E!, ESPN, Esquire Network, Food Network, Fox Business, Fox News, Fox Sports, FYI, HGTV, History, IFC, Investigation Discovery, Lifetime, LMN, MSNBC, Music Choice, NBC, NBC News, OWN, Science Channel, Sundance TV, TLC, Travel Channel, Velocity and WE TV.

Today’s announcement complements Comcast’s recent beta launch of Watchable, a national ad-supported streaming service that offers brief made-for-Internet videos to customers with its X1 set top boxes as well as non customers.