"About iTunes 11.3
iTunes 11.3 includes all-new iTunes Extras for HD movies. iTunes Extras can include behind-the-scenes videos, short films, high-resolution image galleries, director's commentary, scenes, and more. These immersive iTunes Extras can also be enjoyed on Apple TV with Software Update 6.2 now, and will be available on iOS 8 this fall.
New iTunes Extras will be automatically added to your previously purchased HD movies as they become available- at no additional charge.
For information on the security content of this update, visit: support.apple.com/kb/HT1222
(no iTunes 11.3 doc there. May be boilerplate)
File Size: OS X (239.6 MB), Windows (112 MB), Windows64 (113.5 MB)
- OS X version 10.6.8 or later
- 400MB of available disk space
- iTunes in the Cloud, iTunes Match, iTunes Radio availability vary by country
- iTunes Radio requires OS X version 10.7 or later
- iTunes Extras requires OS X version 10.9.3 or later"
FYI: As is often the case after updates, the iTunes for Mac forum has several threads on problems (beachballing, high CPU usage, especially related to Podcasts in list view). I don't really use iTunes anymore so avoiding this update for now. (Are the Extras always streamed from apple's server and not stored on your Mac's drive?)
Apple TV also updated for iTunes Extras. (Added to AppleTV 6.2 update info - see below.)