Warner Bros. is hoping to leverage the popularity of social networking juggernaut Facebook by becoming the first Hollywood studio to offer movies directly through the site. Facebook users will be able to purchase and rent titles from the Warner Bros. catalog using Facebook Credits and play, pause and resume the movies through their Facebook account for up to 48 hours from the time of purchase. An initial test offering of The Dark Night to fans who "Liked" said movie on Facebook can now rent the title through the movie's official Facebook page, with additional titles to be made available in the coming months.

With over 600 million registered users – more than half of whom, according to Facebook founder and CEO Mark Zuckerberg, use the site every day – contributing to Facebook currently being the most-visited site on the Web, it's not surprising that Warner Bros. is keen to tap into such a this huge potential. And with Facebook retaining 30 percent of all the revenue earned through its Facebook Credits virtual currency, the service will obviously be mutually beneficial.

In addition to being able to watch purchased movies in full screen, users will also have full Facebook functionality to let them post comments on the movie, interact with their Facebook friends and update their status. Over the 48-hour rental period, users will also be able to pause the movie, log out of their Facebook account and pick up where they left off when they log back in.

"Facebook brings compelling attributes to video and web TV distributed on its platform. It would immediately mix the social and TV in a way that would be interactive and viral, drawing on its thriving developer community to enhance the proposition further with attractive applications," says Ovum Principal Analyst, Eden Zoller, who believes the Warner Bros. deal marks the start of a more concerted move by Facebook into video services and web TV.

However, Facebook hasn't announced plans to launch a paid video service of its own. The movies offered through the rental application, which Warner Bros. developed independently of Facebook, will be hosted and streamed via a third party. But with more and more users getting their video fix online and Facebook already claiming a spot in the list of top 10 video sites in the U.S. relying only on user generated content, the Warner bros. announcement isn't likely to be welcomed by existing online video services such as Netflix.

The Dark Knight test offering is currently restricted to Facebook members in the U.S., with the cost per rental 30 Facebook Credits (US$3), which is the same price charged by Apple's iTunes Store to rent the movie. Warner Bros. says it will make additional titles available for rental on a regular basis over the coming months – The Social Network, released by Columbia, won't be one of them.