Aside from the moral dilemma of whether Kurt Gerron should have made that film, this documentary also is an excellent object lesson about what happens when you try to negotiate with evil, when you hope that bad people will reward you without further benefit to them.
Gerron did seek the guidance of the community's elders and they counseled him to make that film and admittedly he saw no upside to not cooperating. Still, he didn't even have the Nazi's word about his survival, only a wish that appeasing them would lead to their generosity later. Britain and France tried that on a macro level earlier with similarly tragic results. Evil people seek what benefits them solely; others have no value except as they can be used to obtain what evil people want. Gerron's value to the Nazis exceeded their loathing for any of his people until he finished the Nazis' movie, then he was only something to be despised and purged -- likely as payback because they had to act contrary to their natural desires to get his film.
This is an old lesson, often retold. In Scripture we read of Korihor, someone the devil used to spread false information but finally was killed. "...and thus we see that devil will not support his children at the last day..." (Alma 30:60).