Complex sentence: With a steady supply of different films, exhibitors finally had the ability to open venues where films were the central attraction and did not have to worry about finding new audiences because the same audience would return again and again to watch different films.
Split into simpler sentences: With a steady supply of different films, exhibitors finally had the ability to open venues where films were the central attraction. They did not have to worry about finding new audiences because the same audience would return again and again to watch different films.