If you’re a Mac user with a large iTunes video library and limited storage space, you might appreciate a new feature in macOS Sierra that lets iTunes automatically take care of leaving those videos you’ve watched up in the cloud to free up space on your Mac’s hard drive. A new option, Automatically delete watched movies and TV shows, can be found in the Advanced section of your iTunes preferences, and it’s pretty self-explanatory; when enabled, you basically give iTunes permission to automatically clean up any movies or TV shows you’ve downloaded from the iTunes Store once you’ve watched them.
It’s worth mentioning that this setting only takes effect when iTunes and macOS determine that you’re low on space — much like the space optimization found in iOS, if you’ve got lots of free space available, there’s no need to remove anything from your hard drive just for the sake of removing it. This setting also only applies to movies and TV shows you’ve downloaded from the iTunes Store, of course, since those can be re-downloaded or streamed from iTunes in the Cloud should you want to watch them again; naturally you wouldn’t want iTunes arbitrarily removing videos you’ve encoded and added yourself, so those will be left alone regardless of whether this setting is enabled or not.