While the famed music producer has won 16 GRAMMY Awards working with the likes of Celine Dion and Whitney Houston, he admits in the doc that there are occasionally fans who will recognize him from somewhere else: his stint on The Real Housewives of Beverly Hills with then-wife Yolanda Hadid.
"What I want to say is, 'Hey, I've got 16 f***ing GRAMMYs, I've sold half a billion records. F**k that show," he admits in the film.
Foster explains that he agreed to be on Real Housewives because Hadid wanted to, and "I didn't want to be the guy to say no."
"My reasoning behind it was, do everything you can, try everything you can, experiment and experience everything you can," the producer added, while speaking with ET's Kevin Frazier this week. "Life is short."
Off the Record also touches on Foster's split from Hadid -- the pair divorced in May 2017 after five years of marriage -- and the claims that he left his wife due to the effects of her chronic Lyme disease.
"How can I leave a sick woman?" he says in the doc. "The fact of the matter is that was not the reason I left. It was for a different reason — which I will never disclose — that had nothing to do with her being sick."
Foster remarried in 2019, wedding actress and singer Katharine McPhee, 36, and he marveled to ET about the relationship and the couple's recent one-year anniversary.
"There's 10 things that can bring a marriage down. One of them is an age difference, and it's no secret that we have a big age difference," the 70-year-old producer said, acknowledging the 34-year gap between him and his wife. "Our other nine things of the 10 are really solid."
"She's very evolved," he added. "It's just the truth."
As for his epic music career, Off the Record features interviews with some of Foster's A-list friends and collaborators, like Barbra Streisand, who recalls how the young producer impressed her during a recording session in the '70s, "in true David Foster fashion, being the little manipulator that I was," Foster laughs.
Streisand was unhappy with one of her arrangements, so Foster subtly won her over by sitting at the piano over the lunch break, playing it his way to try and catch her ear. When they returned to work, Streisand recalls telling her team, "Let's do it the way this guy was playing it." The pair became longtime collaborators, and Foster won one of his GRAMMYs in 1987 for his arrangement of "Somewhere" from West Side Story for Streisand.
Foster admitted to ET, however, that his musical instincts have lead him wrong once or twice. When working on arguably his biggest hit, Whitney Houston's cover of "I Will Always Love You" for The Bodyguard soundtrack, Foster says he butted heads with her co-star, Kevin Costner, who thought Houston should begin the song a cappella, with just her voice carrying the tune.
"I said to him, 'That's the stupidest idea I've ever heard -- I'm gonna do another version where I put music around it,'" he recalls. "Then I was standing there, and she went, 'If I...' and I was like, oh my god, yeah, he was right."
See more from the documentary -- including how the producer travelled to Montreal to find a young Celine Dion "singing in a tent," kicking off a decades-long partnership that led to other massive hits -- in the clip below.
David Foster: Off the Record is streaming now on Netflix.