Desc: One Chance to Win: Directed by Charles Bush. With Tony Distefano, Pierre Karsmakers, Brad Lackey, Marty Smith. The 1975 AMA 500cc National Championship Series will go down in the history of motocross as one of the most exciting and controversial in the sport's history. A young filmmaker named Charles Bush decided to follow the series that year with his crew to make a documentary film about motocross.