The astonishing thing about “Gilbert” is the behind-the-curtain record it provides of the real Gilbert Gottfried. As opposed to the eyes-wide-shut, screeching maniac famous for his politically incorrect stand-up routines and his voice-over work as the parrot Iago in Disney’s “Aladdin” and as the Aflac duck — although that latter gig famously blew up due to some untimely tsunami jokes. (More on that later.) All these years, whether he was doing stand-up or participating in comedy roasts or doing talk-show guest appearances, Gilbert stayed locked in the “Gilbert” persona. Like Buddy Hackett before him, he would persist in using a distinctive, cartoonishly exaggerated voice. Even when Gottfried spent a full morning on the Howard Stern show, disrupting interviews and chiming in on the news with hilarious and often wildly inappropriate comments, he would deflect personal questions and remain in character. In Neil Berkeley’s fascinating, very funny and sometimes quite melancholy “Gilbert,” we get to see the hunched-over, eccentric, surprisingly thoughtful man behind the comedic myth — and while he’s just as strange as we imagined he’d be, he’s also a loving husband and a devoted father to two wonderful and seemingly very well-adjusted children. We spend an equal amount of time with Gilbert on the road and in his home — a beautifully appointed, $3 million townhouse where Gilbert shuffles about in his robe, trading banter with his patient wife Dara and playing with his children Lily (10) and Max (8), who delight in spending time with their father and have reached the age where they realize he’s a “character” as well as a character. “There’s toys of him and stuffed animals of him,” says son Max with a smile. Even Gilbert seems surprised at the normalcy of his home life: “Quite often I look at my life like a ‘Twilight Zone’ episode, where the guy wakes up in a totally different world,” he says. We get a solid recap of Gottfried’s career, which started when he was still a teenager playing the clubs in New York. Comics such as Lewis Black, Joe Piscopo, Howie Mandel, Artie Lange and Patton Oswalt comment on Gilbert’s unique, fearless style, and his utter strangeness.