As already posted, movies are on the beach in front of the Beach Club. There's also a campfire with marshmallows. If the weather is bad, they show the movie in the solarium.
At BLT, I've seen them set it up in the grass under the bridge between BLT and the Contemporary Tower. But that may have been a temporary location that one time.
The resort activities sheet in your check-in paperwork will have the details.