It's what pdpfilms said.
If what you are trying to do is keep a TV show (or any media) that was synched to your aTV, it's easy: Just change the sync settings in iTunes to synch selected tv shows. When the next sync happens, iTunes will leave any unchecked media on the aTV.
The nature of synching is to have a master and slave -- in this case, iTunes is the master. When "sync all TV shows" is checked, iTunes makes its slave, aTV, reflect its environment. When you remove media from iTunes, it disappears from aTV. Changed the settings from "synch all" to "synch selected" breaks this master-slave mirror.
-- Mikie
aTV 160
MPB Pro
iPhone
AExpress
500 GB USB2 external