iTunes Watcher will keep your Apple TV in sync with iTunes when new movies are added. It watches the "Automatically Add to iTunes" directory and when a file is deleted from this directory (which is what iTunes does when you copy a file to this directory, it moves it to the appropriate iTunes directory) it waits for a user defined "settle time" and then tells iTunes to sync with the Apple TV. Use MetaX with iTunes Watcher and keep it all synced.