What I really came back to say was more on the subject of 'watching with an open mind'.
A person can only watch with their own mind. A mind formed by their own particular genetics, socialisation, learning and life experiences. No-one is able to watch with a blank slate for a mind, because we are people, not blank, inexperienced, unbiased automata.
It seems to me that in stating his mind is 'open', your DH is actually seeking to make a false claim that his mind is unbiased.
This is not and cannot be the case, because he is a human being.
What I think he is in fact telling you, is that he does not recognise his own biases, prejudices, influences, or the lenses he chooses to look at some things through. He cannot name them.
He can name one of your influences, or lenses; feminism. The thing about knowingly learning about a perspective like feminism, is that you know you are using it as a lens to view things through. You may be able to put on and take off that lens, to use a feminist analysis and to look at things without one.
You can name some of your DH's lenses and influences; patriarchy, societally normalised misogyny and, from what he seems to be saying, an overt masculinism he has freely chosen to adopt, that causes him to hear, believe and favour men over women.
Why not point that out to him?
Further, when a masculinist viewer watches something made from a masculinist perspective (I can't comment on this documentary, haven't seen it), what is happening is that a very narrow, masculinist 'conversation' is taking place, between film-maker and viewer. One saying 'the way I see it, it was like this'. The other saying 'of course mate, see your point completely'.
That is the very opposite of looking at the available evidence with an unbiased mind.
Rather, it is listening to a story, that has been written to comfort, reassure and please you.