The iTunes movie service of Apple has been updated with cloud-delivered extras that make it easier to watch the bonus features like the behind-the-scenes videos and cast interviews on Apple TV.

It is more than timely as the update coincides with the arrival of a movie which has had a lot of buzz: Snowpiercer. The film is in the midst of a limited US release before it hits video on demand this week.

The film is an apocalyptic tale of the last of the living humans and the train Snowpiercer that they survive on which is constantly moving. It is directed by South Korean director Bong Joon-ho.

That wide digital release would mean that in addition to hitting iTunes, Snowpiercer will also be available via Amazon, Vudu, Google Play and YouTube and also on Microsoft Xbox and Sony PlayStation game systems.

But Apple also hopes that movie lovers will opt for buying the high-definition version of the film on Apple TV since it has exclusive extra content that is available at the film's launch. In addition to interviews with Chris Evans, there are other short videos about the film along with concept art from the film.

The extras are much more than exhaustive and also far short of what we can expect on the Blu-ray Disc release. But movie lovers cherish every little bit of extra content. "The launch coincided really well with Snowpiercer because we were launching in their platform at the time when they are really bringing extras to the front", says Caroline McKenzie, director of marketing for Radius-TWC which is distributing the film.

The iTunes Extra revamp is also pretty timely since Apple TV is falling behind its competitor Roku in the race of streaming media. In US broadband homes which have a streaming media player, 44% used Roku in 2013, while 26% used Apple TV, according to the research firm Parks Associates. That is a greater gap than in 2012 when Roku was on 37% whereas Apple TV was on 24% share.