For fans who remember Lindsay-Hogg’s film, or have read dismal anecdotes in any of dozens of Beatles books, Jackson’s scenes of lighthearted antics and creative breakthroughs jump off the screen. We see the Beatles cracking each other up at the mic, mimicking posh accents and performing absurdist slapstick as if in a “Monty Python” skit.

“You see these four great friends, great musicians, who just lock in and develop these songs, and you see it all onscreen,” Jackson said.

Day after day, new material takes shape. Polishing the lyrics to the song “Get Back,” McCartney and Lennon test out names for a character who departs his Arizona home: Jojo Jackson, Jojo Carter, Jojo Daphne. Shaving off the last name gives McCartney enough syllables for some more specificity in the story: “Jojo left his home in Tucson, Arizona …”

Lennon, chewing gum, glances up to ask: “Is Tucson in Arizona?”

The original “Let It Be” was shot on 16 millimeter film and blown up to grainy 35 millimeter. Generations of fans, if they’ve seen it at all, have had access to the movie only in crummy bootlegs transferred from videotape. It has never been officially released on DVD or in online formats.

I told Jackson that when I finally saw “Let It Be,” 20-odd years ago, my local video rental shop required a $100 cash deposit. Jackson grabbed a vintage VHS copy and said he had long regretted not buying it when visiting the United States in the early 1980s, but the format was unplayable on his machine in New Zealand. While making “Get Back,” he tracked down an original on eBay for $200.

“I don’t have a VHS machine,” he said, “so I still can’t play it.”

Jackson’s restored images in “Get Back” are strikingly clear, and help flesh out a story of creative anxiety and creature comforts inside Fortress Beatle. Attendants pour glasses of wine as the musicians rehearse; Yoko Ono paints Japanese calligraphy while Lennon and McCartney, a few feet away, yuk their way through “Two of Us” in goofy accents.