DVD and Blu-ray discs remain the largest source of movie industry revenue (61% in 2012). This year, research shows that this year movie producers are expected to earn $29.4 billion from TV and home video sales.  Online distribution (through iTunes, Amazon, Netflix, direct, i.e.) is also becoming a powerful component of the sales mix and online distribution will increase from 5.6% of total revenues this year to 16.6% in 2018 - that's a stagering 260% from $3.5 billion to $12.7 billion in 2018.

That said, promoting DVD (and online distribution) on and offline continues to be an important part of the movie marketing mix. In the past we have deployed a number of Facebook applications in the the movie industry, the include tabs promoting movie soundtrack and digital content promotions.  This recent application developed for Lionsgate's Dreams the Movie is focused on promoting DVD and online distribution, you can check it out here: http://meta2.us/dreams-movie

Sources:

1. As Digital Video Gets Increasing Attention, DVD and Blu-ray Earn the Lion's Share of Revenue (THE NPD Group)
2. Online Movies: 2014 The Internet as a New Distribution Channel for Movies (Generator Research)