Hi, have you seen the movie? It is a hybrid. Documentary is absolutely one of the main genres due to the fact that the real persons from the events are constant participants in the movie, not just a few minutes in the beginning. Besides, actors are often used in documentaries for re-enactments. Compare it to The Imposter by the same director and you'll see that they are very similar.

Finally, if you know of any "Biography" movies where substantial parts of the movie features the actual persons the movie is about, I would be happy to know of them. Thanks.