Yesterday's announcement by Netflix that it will be adding to its Watch Instantly library past seasons ABC's "Lost," "Desperate Housewives," "Grey's Anatomy" and "Legend of the Seeker" is another step forward for Netflix in strengthening its online competitiveness.

At a broader leveI though, I think it's also further evidence that the near-term success of Watch Instantly and other "over-the-top" broadband video services is going to be tied largely to deals with broadcast TV networks, rather than film studios, cable TV networks or independently-produced video sources.

Key fault lines are beginning to develop in how premium programming will be distributed in the broadband era. Content providers who have traditionally been paid by consumers or distributors in one way or another are redoubling their determination to preserve these models. Examples abound: the TV Everywhere initiative Comcast/Time Warner are espousing that now has 20+ other networks involved; Epix, the new premium movie service backed by Viacom, Lionsgate and MGM, new distribution deals by the premium online service ESPN360.com, bringing its reach to 41 million homes; MLB's MLB.TV and At Bat subscription offerings and Disney's planned subscription services. As I wrote last week in "Subscription Overload is On the Horizon," I expect these trends will only accelerate (though whether they'll succeed is another question).

On the other hand, broadcast TV networks, who have traditionally relied on advertising, continue mainly to do so in the broadband world, whether through aggregators like Hulu, or through their own web sites. However, ABC's deal with Netflix, coming on top of its prior deals with CBS and NBC, shows that broadcast networks are both motivated and flexible to mine new opportunites with those willing to pay.

That's a good thing, because as Netflix tries to build out its Watch Instantly library beyond the current 12,000 titles, it is bumping up against two powerful forces. First, in the film business, well-defined "windows" significantly curtail distribution of new films to outlets trying to elbow their way in. And second, in the cable business, well-entrenched business relationships exist that disincent cable networks from offering programs outside the traditional linear channel affiliate model to new players like Netflix. These disincentives are poised to strengthen with the advent of TV Everywhere.

In this context, broadcast networks represent Netflix's best opportunity to grow and differentiate Watch Instantly. Last November in "Netflix Should be Aggressively Pursuing Broadcast Networks for Watch Instantly Service," I outlined all the reasons why. The ABC deal announced yesterday gives Netflix a library of past seasons' episodes, which is great. But it doesn't address where Netflix could create the most value for itself: as commercial-free subscription option for next-day (or even "next-hour") viewing of all prime-time broadcast programs. That is the end-state Netflix should be striving for.

I'm not suggesting for a moment that this will be easy to accomplish. But if it could, Netflix would really enhance the competitiveness of Watch Instantly and its underlying subscription services. It would obviate the need for Netflix subscribers to record broadcast programs, making their lives simpler and freeing up room on their DVRs. It would be jab at both traditional VOD services and new "network DVR" service from Cablevision. It would also be a strong competitor to sites like Hulu, where comparable broadcast programs are available, but only with commercial interruptions. And Hulu still has limited options for viewing on TVs, whereas Netflix's Watch Instantly options for viewing on TVs includes Roku, Xbox, Blu-ray players, etc. Last but not least, it would also be a powerful marketing hook for Netflix to use to bulk up its underlying subscription base that it intends to transition to online-only in the future.

Beyond next-day or next-hour availability, Netflix could also offer things like higher-quality full HD delivery or download options for offline consumption. Broadcasters, who continue to be pinched on the ad side, should be plenty open to all of the above, assuming Netflix is willing to pay.

I continue to believe Netflix is one of the strongest positions to create a compelling over-the-top service offering. But with numerous barriers in its way to gain online distribution rights to films and cable programs, broadcast networks remain its key source of premium content. So keep an eye for more deals like the one announced with ABC yesterday, hopefully including fast availability of current, in-season episodes.