Complex sentence: This results in a longer film on the same spool, but as a result, there are no printed frame numbers, and moreover, it cannot be used in unmodified old cameras that have the red window as frame indicator.
Split into simpler sentences: This results in a longer film on the same spool. As a result, there are no printed frame numbers, and moreover, it cannot be used in unmodified old cameras that have a red window as frame indicator.