Asif Kapadia's doc on the late singer opens nationwide on Friday.
This is Amy Winehouse at her best.
The late singer is the subject of Asif Kapadia's new documentary Amy, opening nationwide on Friday, and a never-before-seen clip from the film is giving viewers an inside look at a 2006 recording session with Winehouse and producer Mark Ronson.
See the moment Winehouse recorded "Back to Black" in the video below.
WATCH: Amy Winehouse Doc Is Both Heartbreaking and Hilarious
Winehouse wrote the iconic track about her then-boyfriend (and future ex-husband) Blake Fielder-Civil. "I had these feelings, I had these words floating around in me," she says in the clip. "You write a song, you have to remember how you felt. You have to remember what the wind was like, you have to remember what his neck smelled like. You have to remember all of it."
Ronson spoke to director Kapadia for the film and can be heard in voiceover saying, "She would tell me stories about Blake and this tempestuous relationship. That first day, she wrote 'Back to Black,' all the lyrics and the melody, in two or three hours."
WATCH: The Haunting Trailer for 'Amy'
Kapadia spoke with ETonline about the powerful moment in a recent sit-down.
"I really just love her singing live," he said. "It's not a series of album versions of the song, it's actually the moment that she records 'Back to Black' that we found. It's so powerful having her voice a cappella singing, and she's actually reading the lyrics 'cause she's not really learned them, she's still learning her own lyrics. There's a lot of really beautiful moments that come out of the true honest moment of her being creative at that point in time."
For the director and editor Chris King, choosing the film's soundtrack required a bit of sleuthing.
"It's quite a tough decision, to pick the songs and track them in the movie so they feel like they come at the right point in the narrative," Kapadia said. "The songs almost came first. We had the songs, we knew the lyrics, we knew that they said certain things and actually it was like a detective having to unravel, 'What is this song actually about?'
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"A lot of it was unpicking the songs and finding a way to visualize them and then having the tough decision to figure out, where do the well-known songs go and where do we put the first album?" he added. "If you're a fan of Amy, you'll know the first album -- but then there are other songs like jazz standards or, then she does these amazing Donny Hathaway covers and she sings other people's songs, and it was a really tough decision."
See more from ETonline's interview with Kapadia in the video below to find out why you'll laugh just as much as you'll cry through the doc.