Here's why:
* Concrete nouns refer to things that can be perceived with our senses (sight, touch, smell, taste, hearing). You can see a movie, hear the sound, feel the seats, etc.
* Abstract nouns refer to ideas, concepts, qualities, or feelings that cannot be directly perceived with our senses.
While a movie can be a representation of abstract ideas, the movie itself is a tangible thing, making it a concrete noun.