Horseracing is American's number one spectator sport. In 1982, more that 77 million people wagered almost $12 billion at the nation's racetracks. Frontline gives an insider's look at the 'sport of kings,' focusing on tracks at Belmont, NY, where the rich indulge their interest in racing, and at Great Barrington in Massachussetts where infirm horses run for purses that can barely pay the feed bill.