But if you select the director, why is he incapable of acting in the movie he is directing? It has happened a lot in the history of movies, often to great effect. Look at Tarantino, Mel Brooks, Kevin Costner (Dances with Wolves), Mel in Braveheart, etc. I can see if other people want to use your director as an actor in their movie, that he would be off limits, but if he's already on your set anyway, why can't he act in the scene (especially in a limited role)?