Quite often in Los Angeles at the end of a screening, particularly at a local film festival premiere, there’s a Q&A with the filmmaker and cast. But when the curtain goes down at the Tribeca Film Festival, as was the case Wednesday at the event’s opener "Live From New York!," there’s Ludacris. And by Ludacris, we mean the "Furious 7" star and hip hop artist. Once the credits ended to the "Saturday Night Live" documentary, the lights went ablaze and Ludacris started his concert by ordering the crowd to bounce along with him.

It was an ironic fireworks finale to what was a very New York-centric and poignant film. Rather than just hit the audience over the head with a bunch of "Best of" "SNL" clips, Bao Nguyen in his feature directorial debut showed the cultural and political impact the NBC late night show had on the country throughout its 40 years on the air.

"The m.o. was to see 'SNL' as a time capsule of American history. Going back and watching episodes is not only like taking you back to a certain year, but that particular week in time,” Nguyen told Deadline. The filmmaker was approached to direct the film by producers Sarah Cowperthwaite and Tom Broecker, the latter a costume designer for "SNL" since 1994.

Nguyen captured a plethora of priceless moments. There’s an early Tom Snyder interview where "SNL" executive producer Lorne Michaels introduces the 1975 cast Chevy Chase, Dan Aykroyd, John Belushi, Gilda Radner, Laraine Newman, Garrett Morris and Jane Curtain then complete unknowns to U.S. audiences. One sequence explains how Michaels would nudge the writers to write more scenes for Morris, who was being underserved with parts on the show. In another moment, Will Ferrell confesses how his goofy imitation of George W. Bush may have sympathized the president’s reputation, provoking voters to elect him for two terms.

But the most pivotal moment in "Live From New York!" that triggered tears throughout the Beacon Theater was when the doc went behind the scenes on "SNL's" season premiere on Sept. 29, 2001 after the Sept. 11 attacks. In the doc, "SNL" director Beth McCarthy Miller breaks down, describing the emotional atmosphere when the firemen took the stage with then New York Mayor Rudolph Giuliani. “It was as though they had been through it all with their 1,000 yard stares,” she says.

At the "Live From New York!" after party, Michaels told Deadline that when it came to "SNL" returning to the airwaves following Sept. 11, “I called the mayor. I knew we had to start. Comedy is on some level the voice of the powerless. For us it was about coming back and going back to normal.”

Giuliani told Deadline, “David Letterman called me (first) and asked if it was OK for him to go back on the air. I told him not only should you go back on the air, but it would be good for the city. Letterman gave a beautiful talk about how I handled things during his show. Lorne then phoned me after Letterman and asked ‘What do you think if we go back on?’ I said it was a very good idea. Lorne continued, ‘If we go back on and did it in the right way, would you work with us to make it appropriate?’ I said yes and I put him in contact with my press secretary. They came up with the idea of the firefighters appearing on the show, the singing of the patriotic song (Paul Simon’s “The Boxer”), and having me, the fire commissioner and the police commissioner on the show.”

Most of the "SNL" cast who showed up Wednesday night –Kate McKinnon, Bobby Moynihan, Beck Bennett, Leslie Jones, Aidy Bryant and Sasheer Zamata — as well as Michaels were watching "Live From New York!" for the first time. The doc was conceived completely separate and without any correlation to the "SNL" 40th Anniversary special. In allowing a doc crew full access behind the scenes, Michaels said, “It was a film from someone I trusted, Tom Broecker. In regards to the direction the doc took, I had nothing to do with it. The film was a nice surprise and I found it to be a moving and serious film.”

Further expounding on how he had full access, Nguyen said, "Nobody ever told us ‘You can’t talk about this’. We tried to push every button, but we weren’t trying to do a tell-all gossip story on 'SNL.' We got some of the back stories on certain sketches and moments that reflected American history.”

Given the docs eloquent tone and reverence toward "SNL," the one area it sidesteps are the notorious back stories on the drug culture at "SNL" during the late 1970s.When asked whether the doc crew even investigated this in the show’s current climate, Moynihan cheerfully exclaimed, “It’s not like that over there anymore!

Bennett backed him up, saying, "Yeah, were just a bunch of boring hard workers."

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