I suspect you can make use of a on-change microflow.
Whenever you select an enumeration option, you can execute the microflow and retrieve the movies which are in the category you selected. You can show this list of movies on the page you're currently on, or show a pop-up with the movies.
I would also suggest not to use an enumeration for Categories, but to also make an entity for this in your domain model, and link your Movie entity to the Category entity via an asociation. Put a reference selector on your Movie_NewEdit page, to link it to your Category entity (instead of the enumeration)
Then, create Category_Overview and Category_NewEdit pages, so you can manage categories during runtime, which has the big advantage that if your categories change in the future, you won't have to change your model and do a new deploy, but you can change it in the application itself.