A new Plex feature syncs watch states and ratings across multiple servers. If you own more than one Plex server (or log in to a friend’s server), any movies or shows you complete will gain a “watched” marker across all your libraries.
This data will also sync between your private libraries and Plex’s Movies & Shows service. So, if you watch Happy Gilmore on Movies & Shows, it will be marked “watched” on your servers (assuming you have a copy of Happy Gilmore). The same will happen if you manually tag a show as “watched” in Discover.
Now, this feature won’t sync a video’s progress across servers. It only syncs the “watched” marker and your ratings. And syncing doesn’t work for managed users—you know, friends or family who have a profile on your server but don’t own a Plex account.
Thankfully, Plex makes this new feature optional. You can enable it by entering Settings, going to “Account,” and finding the “Sync My Watch State and Ratings” option in the Plex web app. (You can also enable this feature from the Plex mobile app.)
This feature requires Plex Media Server v1.27.2 or higher, and it only works if you have Plex’s metadata agents enabled. Note that watch states won’t sync from your friends’ servers if they don’t have syncing enabled.
Source: Plex
