Hi Danelle,
Disney's Beach Club Resort is such a lovely place to stay! Seeing the Movies Under the Stars there is a real treat. They take place on the beach, which is a great setting for watching movies.
The start time for movies at night at the Walt Disney World Resorts depends on time of year, and at what time it gets dark. Although I cannot guarantee the time they will start in August this year, in recent years in August start times have been around 9:00 p.m. You'll need to consult the recreation activities guide that you receive upon check in for exact movies and start times.
While you can see the high fireworks from Illuminations: Reflections of Earth, the fireworks show at Epcot, from the beach, I do suggest seeing fireworks shows from within the theme parks. It's a nice bonus to see the fireworks from the beach, but in my opinion, it does not replace seeing them from inside the theme park.
As to what else to try at Disney's Beach Club Resort, definitely spend some time at Stormalong Bay, the amazing themed pool which includes a shipwreck-themed water slide. You might also enjoy taking advantage of Bayside Marina, at which you can rent many different watercraft, including family pontoon boats or mini power boats, to use on Crescent Lake. Finally, take a stroll over to
Disney's BoardWalk to rent surrey bikes to pedal around Crescent Lake. You can rent a bike for the whole family and challenge yourselves to work together to pedal up the hills.
There is so much to do at Disney's Beach Club Resort. I'm sure you'll have a great time, Danelle!