Okay, let’s take a break from Hollywood romance. The ‘making-of’ documentary is a subgenre dominated by uninspired filler best buried in the domain of DVD extras, but this gutsy, appropriately chaotic study of the making of one of the greatest and most unpractical films of all time, Francis Ford Coppola’s “Apocalypse Now,” is a rousing exception. Its trump card, of course, is footage from the shoot shot by Coppola’s wife Eleanor, providing a fascinating first-hand account of a genius raising his game as he loses his mind.