Complex sentence: Downhill Battle is a non-profit organisation launched in August 2003 which believes the four major recording labels have a monopoly that is bad for both musicians and music culture, but they also believe that they have an opportunity to change that.
Split into simpler sentences: Downhill Battle is a non-profit organization launched in August 2003 which believes the four major recording labels have a monopoly that is bad for both musicians and music culture. They believe that they have an opportunity to change that.