[Bernas]

n. pl. doc·u·men·ta·ries

A work, such as a film or television program, presenting political, social, or historical subject matter in a factual and informative manner and often consisting of actual news films or interviews accompanied by narration.

If you had changed the bold part to selective and persuasive then I would agree with you that he is a gifted documentary filmmaker.

I'll give you that he is a gifted filmmaker.