With a strong persona that resonates with peculiar humor and undying intrigue, McElwee can easily become the focus of the film. While it doesn't work to get across the greater meaning in the film world, his film translated into literature may work brilliantly. If it were written, we'd be able to see more clearly the structure: McElwee wants to find the truth about his family history. McElwee searches for it in North Carolina via numerous interviews. McElwee finds the truth and is "dogged." People continue to smoke. And so on.
This linearity gets tripped in the film due in part by McElwee's own meanderings, and also in part by his choice of sound and visual clips, or his editing. McElwee splays on after finding that the original film, Bright Leaves, was not about his family. He's dogged by the thought and also by...wait for it... a dog. So much so that he restarts the scene, sans dog. Were this to be edited properly, say, in a literary form, it's unlikely that McElwee would repeat the scene, once with a dog and once without.
There is also a clip in which McElwee asks an older woman (her name is escaping me) about his grandfather. He asks: "Did he have a sense of humor?" The woman responds: "Now, I don't know about that, but I do know he lost his teeth." In the scene immediately after that, he cuts to the old woman saying, "Oh look! A black cat!"
These clips do, in fact, provide great humor for some, but if this were a literal form of the story, McElwee would really have to sit with that and ponder the importance of the clips or quotes. His digression may offer humor to the film, but it makes the overall story drag. McElwee's persona may make for excellent non-fiction essays, though.