From 1967-1976 their were two top shelf professional basketball leagues in America. The National Basketball Association (NBA) and the American Basketball Association (ABA). This documentary is from 1997 so a little more than twenty years after the merger, but tells the story of the wild and crazy ABA.
If nothing else, the ABA continues to have a lasting effect on the NBA since it was the league that introduced the 3-point shot. The NBA not too many years after the merger, adopted the "gimmick" shot itself. This year about 40% of all field goal attempts in the NBA are 3-pointers.