When Green Day's American Idiot album was turned into a Broadway musical, the initial and understandable response was to snark that Billy Joe Armstrong and company had drifted farther away from their punky Gilman Street roots than anyone could've imagined (read: "SELLOUTS!"), but how does a concept album become a hit musical? You get a glimpse, but not much insight, from Broadway Idiot.
Committing one of the most common sins of documentaries - not telling the viewer when things are happening - Broadway Idiot gives a superficial overview of how the album was adapted for an initial skeptical band (who could've killed the project after extensive work had already be put in if they didn't dig it) and follows as the show is initially mounted by the Berkeley Repertory Theater before moving to Broadway.
While we see the rehearsals and discussion of how to thread a narrative through the album's songs, there's very little solid in the way of insights or struggles shown so it comes off as more of a glossy tour souvenir/fluffy promo piece. That a chunk of the songs came from Green Day's follow-up 21st Century Breakdown is totally ignored, making this a poor source for those unfamiliar with the show's construction. (You really shouldn't need to know so much before watching a documentary.)
Armstrong's stint on Broadway as St. Jimmy is portrayed as the director's dream when in actuality it was a bit of a stunt to goose sagging ticket sales. However, this portion includes the surprising footage of an 11-year-old Billy Joe singing "Send In The Clowns" and "What's The Matter With Kids These Days?" with the revelation that took voice lessons for 10 years and sang Sinatra. This leads the show's music arranger/orchestrator, Tom Kitt, to theorize that Armstrong's songwriting was influenced by his exposure to non-pop music fare.
I've seen the touring production twice (my review here) and while it's a bit of a whiny, dour bummer, the music is solid and really soars when blown out into these arrangements; this is what I listen to over the original albums. If you're a fan of the show, it's worth giving Broadway Idiot a look, but it's too superficial to make it essential or reference-grade.
Score: 7/10. Catch it on cable. (Netflix has it.)