Walsh told Radio.com that after putting the call out to fans for self-shot testimonials in November of 2012, he quickly received about 300 hours of material. He actually watched every single submission.

"I felt very much a responsibility to do so," Walsh explained. "Enormous effort went into [filming those submissions] from thousands of people. I was worried that we were going to get 4,000 hours, that would have been a real problem. Three hundred hours was manageable. Every day we saw something new. Every day was exciting."

Directing the film was mostly an exercise in editing. Walsh spent six months in an edit, and had lots of decisions to make when putting together the final cut. While there's certainly a lot of love for Bruce in the documentary, there were some things that he steered away from.

"There were stories about how generous he is, stuff about 9/11, and he comes off a bit god-like, and I didn't feel comfortable with those stories," Walsh said.

"I think this film doesn't build Bruce to be a god. There's an undercurrent that he's a very decent man, and that does come across in the stories that are told. It's just very heartfelt stories of people talking about how Bruce and his music has affected their lives. One guy from Israel says, 'Bruce taught me how to be a man � a decent man.' That's who Bruce is.