Movie buffs who play this documentary on the making of Apocalypse Now after they watch the movie itself may have a difficult time deciding which is better or more compelling. That's how revealing and powerful Hearts of Darkness is. Director Francis Ford Coppola's wife, Eleanor Coppola, audiotaped and filmed her husband, often in secret and at his most agonized moments, during the making of this most agonizing film. A brief recap: Star Martin Sheen had a heart attack and a nervous breakdown. A typhoon devastated the film's sets, closing down the film for about three months. The film's backers, United Artists, threatened to pull the plug on the film. The Philippine army kept withdrawing its helicopters to fight a real war against guerrilla insurgents, killing the film's schedule almost as much as the typhoon. Star Marlon Brando arrived way overweight, didn't know his part, bogged the film down with incessant questions and improvisation, then made off with one million dollars a week when he went over schedule. The documentary relays all of this with depth, insight, and sensitivity. It leaves a final impression of Coppola as a heroic and remarkably brave man who built around himself a community of very fine and dedicated artists and created one of the greatest films of all time.