For this argument to be persuasive (regardless of what side is being argued) hearing personal experiences and opinions can be powerful, and film is the best medium to show those personal statements. Through film people involved with opinions can talk directly to the viewer, which reduces bias in the argument. Film is powerful because one person (the filmmaker) can talk to someone that is otherwise difficult to talk to, and then bring the viewers of the film into the discussion. Because it provides a direct link from the audience to the speaker, much of the interpretation an author would normally add is eliminated. This will help keep the argument accurate.
I had an experience related to this in high school. I was asked by the school to work on a film about our basketball team going to the state championships. I interviewed players, fans, administrative staff, and others to reveal the importance of our team, and what it brings to the school. Through that process I was able to show people opinions and viewpoints that they normally wouldn't consider, straight from the source. People were more engaged and motivated to watch this film than they would have been if these ideas were presented as a paper, or lecture or podcast.
In regards to the relevant subject, film would help bring the viewer closer to the players and coaches and administrators that have opinions on these issues. It could bring many influential people together to form an opinion, which is impossible through any other presentation style.
When trying to argue an idea having well respected people join the discussion is always going to add to your argument, and film will help you with that.
@Benbom