I see the ‘delete’ option still appearing on the preplay page of a synced video.
May I ask what type of video it is you are syncing to your device?
Is it movies or tv show episodes?
If it’s tv show episodes, are you watching the episodes strictly in their numerical order?
If so, did you know that you don’t need to delete the watched episodes manually?
You can set up a Sync job which only syncs ‘unplayed’ items.
Which means, once an item has been played it will get erased automatically upon the next Sync cycle.
So the trick is not not sync single episodes, but whole seasons or even whole shows.
If you sync a whole unwatched show, you simply tell plex to sync ‘unwatched’ items only and put in a restriction to e.g. 3 episodes.
The result is that you will always have the next 3 unplayed episodes on your phone - ready to be
Once you are at home or at work where there is WiFi coverage, you can trigger a new sync cycle and the watched episode(s) will get purged and the next unwatched will get added automatically.
And if you have internet connectivity during your commute, your Plex server will know immediately when you have finished an episode. It will automatically start transcoding the next episode - ready to be copied to your phone.