The short film shown by Father in the movie to his soldiers is considered propaganda. What was the purpose of this propaganda?

The propaganda that Father shows the soldiers I mostly for their benefit. Propaganda like this was used to show to the German population to make them believe that the camps were a nice place to live. The propaganda served its purpose well, and the German government indoctrinated their population successfully and brainwashed them so completely as to the truth as we see when Bruno enters the camp and asks where the café is. While the Jews walked into the camp unawares of where they were going, they would have realised pretty soon that it was not a nice place, while the Germans even after seeing it mostly did not realise the horror of what the camp was being used for.

I haven't watched the movie so i'm not sure how accurate this is.