The film is not really a documentary.
The movie was voted as the best film of the festival by a large margin. (And there were some excellent entries this year.)
As far as I am concerned this is the best Lovecraft adaptation I have ever seen.
The film is an adaptation of a number of H.P. Lovecraft's storys intercut with some very realisting looking film footage of "HPL". (Actually an actor who does a remarkable job with the part.)
The film is an exploration of Lovecraft's motivations behind the stories, why he wrote, and what he thought of his own efforts -- intertwingling with his own stories and themes. (Especially the dreamlands stories of Randolph Carter.)
All of this sounds kind of hokey, but it works. Through the Dreamlands, the film mixes modern day and Lovecraft's 20s, among others. (One scene has Lovecraft meeting a modern fan and wondering why his face is on a t-shirt.)
If you can find this playing somewhere, by all means see it! It is an impressive piece of film making.