The update is a welcome one for those who regularly take advantage of the additional content on Apple's MacBook Pro with Retina display, where standard-definition content is at odds with the computer's high-resolution screen. The same is true for the Apple TV and iOS devices, where the behind-the-scenes videos, short films, image galleries, and commentary are often missed.
Consumers who have previously purchased HD movies from the iTunes Store will receive the new content as it becomes available at no additional charge.
Apple first introduced iTunes Extras in 2009 as a way of better positioning the then-nascent digital video store against DVD sales. However, their years-long absence on Apple TV and iOS devices -- especially the iPad -- exasperated many consumers.
iTunes version 11.3 is available now as a 143-megabyte update from the Mac App Store. iTunes Extras on Apple TV require version 6.2 of its own software, available through the Settings menu.