iTunes Extras lets you access bonus content such as movie outtakes, interviews, behind-the-scenes videos, songs and more. It is now available on your Apple TV, and movie studios will be able to add more content to your existing movies down the road.
iTunes Extras on Apple TV
When you buy a Blu-ray movie you are oftentimes treated with bonus content. You can think of iTunes Extras in the same way and it is now available on hundreds of titles in the iTunes movie store.

However, you have to buy the movie to get access to iTunes Extras; renting is not enough. Movie studios will be able to add more extra content regularly if they so desire and it will be added to your previous purchases free of cost, just like all your 720p movies were updated to 1080p versions a few years back.
iTunes Extras is available now on your Apple TV and on your PC/Mac in iTunes. It will also arrive on iPhones and iPads with the release of iOS 8 later this year.
- Source: Variety