This is one of those documentaries that insists on inserting more footage from the film than footage from the people who actually made it. More like an advertisement. And if you're watching it on a Blu-ray (like me) it's intolerable because it's just showing you things that are already fresh in your mind.
Would have much preferred an unedited interviews with Scorcese and Bernhard, with some occasional cut-aways to illustrate their points, rather than every single reference being shown.
Still, if you haven't seen the film in a while, it's probably enjoyable. I just wish we had more from Scorcese -- he always has so much to say, and we only get hints here. (It seems clear to me, reading between the lines, that this film was made as a favour to his friend, de Niro -- he even admits that he only understood the material as they were making it, not before. Would love have heard more about that -- he didn't work with de Niro again for 7 years.)