I have hesitated to chime in with my opinion because I know the limits of film. I have seen even the best documentaries end up leaving pertinent information on the cutting room floor simply because there was not enough time to cover it.
there are a few scholarly articles about BDSM and the dynamics involved, but as these usually approach from the standpoint of studying "Abnormal Psychology" the bias is toward us being abnormal. I am not sure what normal actually is, but I do know that on all standard tests I actually come up as a text book case of sanity. I am apparently so well adjusted that I have no geder or racial bias in my subconscious.
This would be seriously disturbing to me if I did not know myself well enough to ignore these findings. The one thing I do know is that sanity and normality is overrated. Are we, who admit for predilections for kinky sex, less well adjusted than those who deny them? Somehow I think not.
As you research this film you will find that we are seen as numerous things, but that one thing that should never be questioned is the fact that we embrace who we are. This makes us better adjusted in the long run because we can look into ourselves and accept the things that others run from. More than anything else, this is what needs to be told about us.
We, as a group, and as individuals, are generally better adjusted and more stable than those who reject us because of our choices.