From a related article:
The plethora of Nazi uniforms on a show billed as family viewing was regarded as too provocative in the 1970s especially as at one point it describes Nazi Germany as "the most efficient society ever created".
But now 40 years later public broadcaster ZDF felt it could air the show for the benefit of the legions of German Star Trek lovers who have never seen it...
Doctor Simone Emmelius [editorial director at ZDF]... added, however, that the episode was subject to a German FSK-16 regulation. That meant that nobody under the age of 16 was allowed to watch, and it was shown after 10 o'clock at night so the "audience is capable of questioning the complexity of the episode".