How can it be a "brainwash" if the videos simply document what happened?
it's hard to get in a left winger mind but i'll try:
in fact the average left winger is THE ultimate brain-washed person,he is so brain washed from all direction of society that includes the education system,his family,the media and his friends,so that he don't even know he is in fact brain washed,strange isn't it,but its quite common . if he had never stopped for a moment to listen to everybody and started thinking for himself he will never get out of the brain wash machine for the rest of his miserable life.
and back to the propaganda movies:when a left winger see the truth before his own eyes in some movie,he usually starts lying to him self saying "it can't be ,somebody must have edited something here to deliberately divert my thinking towards something negative,i shouldn't watch this movie anymore!,it is fanatical!"
this is exactly how they succeed demonizing the idea of Rabi Kahane ה"יד ,the lack of human thinking for himself is alone enough to get this outcome,the establishment only needs to take care that the population will stay stupid enough,and simultaneously keep on selling a fabricated "truth" to all. this is also how arabs are controlled by their regime,the same trick.and this is also why the left wingers understand and have empathy towards the arabs.
now ,when you start with a movie that seems to be part of the establishment ,a so called politicly correct movie, the left winger is already half hypnotized and are willing to accept the information you are feeding him,and this way,step by step,he is learning about the truth whether he likes it or not.
from now on it is up to him if he memorize the info or not,will he still insist of learning more?,it is his own good will.