Screenwriting : Fantasy by Lawrence R. Kotkin

I haven't seen much, if anything, other than Harry Potter type fantasy films. Drawing the upandcoming adolescent/pre-adolescent into the theater might call for a more relatable setting. I'm doing my first, what would be called YA fantasy that is done in an urban setting. Is that too mundane to have a following?Should I do it as a section from my novel: a short? It's a little like writing a very tight short story. Take it up to the first conflict/event. How long would it be permitted to run to still be a short?