Apple has released the latest version of iTunes, enabling iTunes Extras for HD content purchased in the online store. You can view these features via iTunes or Apple TV once you've updated that device to version 6.2. This content will also be integrated into iOS 8 when it hits devices this fall.
iTunes Extras represent an area where the potential of cloud data storage for content really shines. Films and shows that feature the content get extras like behind-scenes videos, commentary tracks, and a host of other goodies. Since these extras are stored in the cloud, studios can add new content from time to time if they choose, increasing the value of buying a digital movie over just renting it.
New iTunes Extras content will be automatically added to your previously purchased HD movies at no extra charge as it becomes available.
According to the Loop, the following movies already have iTunes Extras content available: 21 Jump Street, 300: Rise of an Empire, American Hustle, Anchorman 2: The Legend Continues, The Bourne Identity, The Bourne Legacy, Captain Phillips, Cinderella, The Dark Knight Rises, Despicable Me, Dr. Seuss' The Lorax, Forrest Gump, Frozen, Ghostbusters, The Incredibles, and Man of Steel. More are being added every day.
You can download iTunes 11.3 right now via the updates tab in the Mac App Store, or directly from Apple.com right here.