However, all movies need scripts. Documentaries don't need feature films, which are strong in story and can arrange obvious conflicts and twists and turns. However, documentaries require complete records and present contradictions and conflicts. Although arrangements are not allowed, these contradictions and conflicts gradually emerge with the progress of the plot. So the story of the documentary is presented before shooting, which is also the reason why people pay attention. At least one complete plan case must be made before the documentary is executed. So you have to write first, then shoot. Personal opinion, hope to adopt.