To dream that you are watching a movie suggests that you are watching life pass you by. Perhaps you are living vicariously through the actions of others. Consider also how the movie parallels to situations in your waking life. Observe how the characters relate to you and how they may represent an aspect of yourself.
To dream that you are playing a role in the movie foretells that something from your subconscious is about to emerge or be revealed. It may also represent memories of images from your past. Alternatively, the dream may be pointing you toward a new role that you might be undertaking. Your subconscious is psychologically preparing you for this new role.
To dream that the movie screen is blank suggests that you are trying to distance yourself from some issue or emotion. Or you are feeling excluded from some situation. Alternatively, the blank screen symbolises a lack of accomplishments. You fee that you have nothing to look back on.
If you have a dream where you are part of an existing movie scene, then it implies that a life situation is playing out similarly to the movie scene. You feel connected to the scene. Consider what you are feeling when you watch the scene; it is this feeling that you are lacking or trying to recreate in your waking life. More directly, the dream may just mean that the movie is on your mind a lot or that you have watching too many times.