Is this (also) the film?

Is this the one where Niven has prepared an animated film to show his gang how the robbery will happen, in which he is seen skipping fearlessly along the roof of the train, but in the actual robbery he crawls along, terrified? If not, which film is that? I remember laughing at the absurdity of the cartoon and then the cowardice of the man. Niven was one of the greats.

I can eat fifty eggs