Leonardo dicaprio actor credit

After watching Les cent et une nuits de Simon Cinéma for a french class I was a little confused as to the actor credit that Leonardo dicaprio has got on imdb for it. I never saw him once in the film or even heard his name mentioned (even though previous imdb poster's have said that they are sure his name was spoken), and he didn't get credited at the end of film credits. So if he has no actual part in the film except some possible picture of him or his name being spoken then why is it an acting credit that he received and not a Thanks...Self credit..or even archive footage like he has in various other things.