Introducing iMovie Theater. It’s your own personal theater where you can show off the movies and trailers you’ve made. They appear as a beautiful display of movie posters, so you’ll always be the star of the show. And with iCloud, they’re automatically on all your devices, even your Apple TV.
To access the new feature, make sure to update to the latest software version and log into your iCloud account on the Apple TV and on the iMovie device you're sharing from.