And to hear, also, about the person behind the sharp-witted, funny man who liked to take the mickey. James worked hard to super-impose a brasher persona over Te Wehi Taitoko, the shy boy who, in his early days as a musician, could "sing like an angel" and play guitar superbly, but couldn't summon up the nerve to even face the audience. He would stand on stage with his back to the crowd.
That's possibly not a well-known aspect of the man who went on to be a seemingly fearless entertainer and, two full decades after his death, can still make a nation smile at the mere thought of his giggle and guffaw at replays of te gags from Te News.
For several years, before his comedy break, James - who went to Whangarei Boys' High School and has been inducted into the school's Hall of Fame - travelled at home and overseas with Maori showbands.
For about three years he was a member of the esteemed Maori Volcanics.
Mune tells how the variety shows in which the Volcanics performed in the UK often featured comedy which had an archetypal music hall character fronting them (think Dexter Fitzgibbons from Radio Times). Mune says James would sit in the audience after the band's gig and study those comedians, their comic timing and audience responses.
"By the end of that tour he had created a new character. The shyest person in the world had become Billy T James."
In making the documentary, the film-making team looked for interviewees who could "bear witness" to each aspect of Billy's life and career.
"When I started contacting people they leapt at it. They wanted to pay tribute," Mune says. "Virtually everyone who worked with Billy had the feeling that they were the person he worked with best - that they were the special friend. In other words, this shy, gentle, retiring man had the same effect on a one-to-one basis as he had working a crowd."
For Mune, often the same themes came to the fore: "The most common theme of all was how much people loved him. We'd shoot the interviews and then back at the studio I'd be watching them and I'd be in tears."
Intense work, and intensely rewarding?
"Hell, yes! The fact it was Bill made it a special task from day one. The thing is, we all loved him. But Billy is still a huge enigma."
At its height, The Billy T James Show was watched by 1.3 million people, half New Zealand's population at the time. Like Elvis, James was "The King", Mune says. "There will never be another Billy T James because not only has this multi-talented person gone, those times have gone, too."
Archival footage, newsreels and drama sequences from the 1950s, 60s and 70s build on that background - evoking nostalgia rather than cringes - but there is also social commentary from Derek Fox, Pio Terei and Jim Moriarty on what James' television exposure meant to young Maori in the 1980s.
Watch the movie, Mune advises, to get an idea on how brave he was in poking borax at his own Maori culture as well as the colonialism which shaped New Zealand. And how he enabled everyone to laugh out loud at political incorrectness without insulting anyone.
"I had to watch some of those gags 100 times, and I was still laughing at them every time I saw them."
Mune worked with James twice, most notably on the film Came a Hot Friday, which Mune directed. James' show-stealing character, The Tainuia Kid, was on screen for only 15 minutes but the pathos and bravado, perfect comic timing, vulnerability and sheer hilarity of the Maori-Mexican Tainuia Kid will forever be a classic.
"When he first turned up on set he didn't know what he was doing, because, compared to sketch comedy, it was serious acting," Mune says. "I said, 'Don't play it for laughs. Be serious, play it like Hamlet', and he took me up on that. He did it. And I saw an acting lesson - the work was beautiful."
Long-time television producer Tom Parkinson first saw James at a late-night gig at Avondale Rugby League Club. He grabbed the Maori clown with the golden voice for the spoofy television comedy, Radio Times.
It was Parkinson who suggested Mune direct and co-write (with Phil Gifford) the documentary. "It was a marvellous opportunity. I have to say it was one of the hardest jobs I've ever done," Mune says. "We were always searching for the movie while we were shooting. It wasn't clear what we would end up with until we got to talk to the people."
It is 20 years since the king of Kiwi comedy died at 42, two years after a heart transplant. The anniversary was last Sunday but the film-makers chose not to be mawkish - they've waited a few weeks to release Billy T: Te Movie, on August 18.
"Neutral land" still holds for Mune some small jitters about how his first documentary will be received but "now, of course, there's not a damn thing we can do about it" - other than offer up a powerful tribute to the man widely considered our greatest ever comedian. Not only the funniest, but the most loved.
