Complex sentence: Where the MSEP ran twice nightly, AOP ran once during the afternoon and again at just prior to the nightly fireworks display, the full length of Disneyland from It's a small world to Town Square at the beginning of Main Street USA.
Split into simpler sentences: Where the MSEP ran twice nightly, AOP ran once during the afternoon and again just prior to the nightly fireworks display. It travelled the full length of Disneyland from It's a small world to Town Square at the beginning of Main Street USA.