"This certainly was a story about a group that I grew up with," he said. "I was just fascinated about how they turned surf music into something that wasn't this little niche that we had, because they added lyrics and incredible harmonies, and so I wanted to discover how that all came together."
At the film's premiere in Hollywood, founding member Brian Wilson earned a standing ovation from fans.
"Beach Boys" bandmates Al Jardine and Mike Love said this whole experience has been an emotional ride.
"To tell you the truth, it made me choke up because two of my cousins are no longer with us," said Love. "Brian's had his problems all along, but recently, as well. These are family members, these are guys who grew up with. I think it really comes across that there still is that love, and will always be, and that's what gave rise to this world class harmony."
Jardine said he enjoyed watching the vintage footage.
"The stuff you find on a shoebox ... just good stuff in there," he said. "It's all about the performances are the reward for the hard work we put in on the recordings. So to see some of that vintage film is really, really wonderful."
"The Beach Boys" is streaming now on Disney+.
Disney is the parent company of this ABC station.