Fanhattan, the slick iOS video discovery app, has broken into the TV Everywhere world, adding content from HBO and Cinemax. Fanhattan users can now discover HBO programs and movies within Fanhattan and click through to view them if they are authenticated as HBO subscribers. Fanhattan is announcing the addition of HBO and Cinemax, plus NBC and CW programs this morning. Fanhattan now has 175K TV programs and movies from 14 premium entertainment apps discoverable, up from 4 apps at launch last year.

Fanhattan is also unveiling a new "WatchList" feature, which allows users to add a movie or TV show and be alerted when it becomes available on any of the 14 sources. For users, WatchList eliminates the confusion around where, how and when premium content is available, as it passes through multiple distribution windows and models.

Fanhattan's CEO Gilles BianRosa explained to me in a briefing last week that with the number of premium video apps growing along with the acceptance of watching on devices on the rise, the value of a comprehensive discovery app to help viewers find the content they love is becoming more critical.

Unlike the web, which is open and enables deep-linking to particular content, apps are isolated islands, making it much harder to present a high-quality discovery experience. Gilles noted that integrating certain apps into Fanhattan has been arduous, requiring APIs to be developed and apps to be re-done in a particular ways in order to expose content.

Fanhattan's hard work appears to be paying off, as Gilles said it's poised to pass its 1 millionth U.S. download soon. From a business model perspective, Gilles likened Fanhattan to other vertical search destinations like Kayak, Mint and Yelp (in travel, financial services and local respectively), using a combination of sponsorships, advertising and affiliate marketing to drive its revenues.

Next up for Fanhattan is expanding beyond its iOS app to the web later this summer. Gilles said even despite the growth in video apps, far more TV and other premium video content still resides on the web, so Fanhattan online will bring a lot more content choices to users.