Here are excerpts from an article by Billy Marshall Stoneking.
The documentary script is often the most underrated aspect of the documentary process. A school of thought suggests that the documentary-making process should be fluid and organic,whereby the filmmaker experiences the film as he makes it.
Many filmmakers write a “paper-edit” their footage after shooting in place of a script. This process has and does work with many types of films. Especially when the filmmaker is recording events beyond his control like political rallies, events, natural disasters, riots and demonstrations etc.
However, in most films, the filmmaker will find him/herself asking the question “What should I shoot?” Here, it is imperative to start out with a well-written script, or narrative concept, even though it may develop and change during the shooting process. As a documentary filmmaker one often finds it is worthwhile to let the people and experiences associated with the film’s story to seep into one’s being, thus allowing the story to write you simultaneously with you “finding” the story. More often than not, preparing a script beforehand can make the difference between a bad film and a good film. Or at best, a good film and a great film.
What is the big idea? What is the source of conflict in the story? What is the struggle of the main character? Who or what is pitted against them? What obstacles must they overcome? What threats do they encounter? What are the source of this threats? Do they come from others or from the characters themselves? How is this conflict presented and played out in the film?
Will it be continuous newly shot footage? Stock video clips? Interviews? Speeches? Narration over stills? Hybrid?
What special qualities does the presenter (or main character/s) bring to the film? Authority? Authenticity?
Who is the film addressed to? To whom is the filmmaker speaking? ‘Everyone’ is not sufficiently specific. Who you are talking to has a very important bearing not only on what you present but the way in which you present it. What assumptions are you making about your audience in terms of pre-existing knowledge and experiences?
What point does the film make? What do you want the audience to go away feeling or thinking about at the end of the experience they’ve had watching the film? Is it to provide an overview or present an argument?