How to: Force-sync a first generation Apple TV with iTunes 12
For anyone else out there who's still using a first generation Apple TV and iTunes 12 and realized there's no longer an option to "force" the device to sync, I have a work around.
Background
With my first generation Apple TV, I "manually" manage the content stored on the device. As well, I don't add content movie-by-movie (song-by-song, etc.). Instead, I have three playlists (Movies, TV Shows, and Music) that I then sync to the Apple TV. The problem is, even pre-iTunes 12, modifying the content of a playlist didn't trigger iTunes to offer to "sync" the device (I don't think it was smart enough to deal with the EOL first generation Apple TV in terms of playlist content changes). But, at least with pre-iTunes 12, you were able to right-click on the device in the sidebar and this would bring up a contextual message with "Sync" as one of the options. So, even though the "Sync" option was greyed-out in the main iTunes window, you could still initiate the sync via the contextual menu (thus "force syncing" the device with iTunes). But, with iTunes 12, this contextual menu has been removed (right clicking does nothing) and thus the ability to "force sync" is gone.
Solution
After trying many different options to get the first generation Apple TV to sync with iTunes (after updating the content of a synced playlist), this is the only solution I've come up with that works:
1. Create a playlist called "ATV Force Sync".
2. Put a single movie in the playlist (I used a short, 10 second video, but I'm sure you could also use a song or any other media—just use something that is short and you don't care if it's on or off the device).
3. To "force sync" the Apple TV, iTunes > Apple TV > Settings > Movies > Sync Playlist, check the checkbox beside the "ATV Force Sync" playlist. This will then enable the Sync"button and you can now force the Apple TV to sync with iTunes (it'll sync the "ATV Force Sync" playlist, but also sync any changes to any other playlist the Apple TV is set to sync with). Then, the next time you want to force sync (i.e., if you've updated the content in a playlist you want to sync), just uncheck the checkbox beside the "ATV Force Sync" playlist, and the Sync button will be enabled again (and so on, enabling/disabling the "ATV Force Sync" every time you want to force-sync the device).
Anyway, it's not an ideal solution, but at least it works. I've filed a bug report with Apple, but let's be honest, I don't think supporting the first generation Apple TV is on their "to do" list anymore. <G>
Hope this helps someone else out there!
Kristin.