I totally agree with Denis888. I just want to add, for those who don't quite understand it, that actors and other movie makers here play themselves (look at credits). Do they play, or is this who they really are? That is the question. I think, they were too serious about the Stanislavsky's method. All of them were celebrities at that time, so many details of their life were a common knowledge in Poland, and as such were not explained in the movie. Also the person of the absent main character Zbigniew Cybulski one of the biggest stars of Polish cinema. His exploits were known very well to general public and were subject of widely spread gossip. He died crushed when trying to jump into moving train, exactly in the way shown in the initial scene of the movie. This scene still gives me goose bumps, 'cause I still remember hearing the tragic news from the radio. Showing this scene so soon after his death took a lot of courage, and was very controversial at that time. Unfortunately, just like majority of Polish movies, it is so much set in specific local Polish reality, and not very transparent to viewers who don't know much about Polish history, and current events, particularly those behind the scene.
I watched this film recently with my 27 y.o. son who currently studies film in college. He was impressed by general idea, camera work and other technical matters, but could not really grasp all the flavor and spice of the movie without extensive explanation of the background events and details about lives of main movie characters.
So, to really grasp it, you need to learn about Polish cinema milieu in 60's. If the behavior of few characters in this movie seems to be somewhat strange, remember that most of these people were survivors of the war were 20% of Polish population was killed, and after the war they were subjected to Stalinist terror. They did not have psychologist to treat their post-traumatic stress disorder. A lot of Wajda work is about people dealing with their demons and different forms adjustment to the new reality. This is one about filmmakers and actors.