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That's really odd. "Other" takes up 561 MB on my AppleTV, and I'm assuming that's the OS itself. I would definitely call Apple support and ask what's up. You could try restoring your AppleTV first...
 
Ok, I found out what it is: A BUG!

While synchronizing, if the procedure doesnt end, then "Other" grows! I have mayn times stopped the synchronization and resumed it again...

The only way I found to reclaim the space is to do a factory reset...
 
Ahhh. Some sort of cache. Had you tried simply resetting your AppleTV? Perhaps it would empty the cache on boot.

(You can restart by holding the "-" button and the Menu button for a few seconds)

I've interrupted syncing several times, but I've also restarted a few times (moving the unit around).
 
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