A new documentary about The Doobie Brothers gives fans an in-depth look at the rock group’s long and fascinating journey.  Available on DVD and Blu-ray, Let the Music Play — The Story of The Doobie Brothers delves into the band’s 40-plus-year career, which has seen the rockers find success with a rotating lineup of musicians while undergoing a number of dramatic stylistic changes.

To help tell the tale, the flick offers interviews with many of the musicians who have been part of the group’s history, including founding members and current band leaders Tom Johnston and Patrick Simmons, longtime multi-instrumentalist John McFee and such respected alumni as Michael McDonald, Jeff “Skunk” Baxter and Tiran Porter.

Johnston recently chatted with ABC News Radio about Let the Music Play, and shared some of his favorite aspects of the film.  The singer/guitarist revealed that getting to relive the group’s early years was among the things he enjoys most about watching the video.

“It’s always fun to look back at the inception of the band,” he notes.  “You know, hear it talked about and how it came together…It’s just fun to look at the old footage.”

Among the most memorable highlights for Johnston was when he and his band mates began hearing their first hit, “Listen to the Music,” played on the radio.  “[It was,] like, a surreal event,” he says.  “[We went] from being nowhere to all of a sudden having national airplay.”

Of course, a major occurrence in Doobie Brothers history took place in the mid 1970s, when Johnston left the band and was replaced by singer/keyboardist McDonald.  As the documentary shows, The Doobies had some of their biggest hits during McDonald’s tenure, which saw the group transform from a roots-rock outfit to a more jazzy and soulful act.  Eventually, Johnston joined a re-formed version of the Doobies, and the band went back to the style it originally had played.

Looking back, Johnston says he thought that it was “pretty cool” that the band was able to remain successful despite the changes it underwent.  He points out, “I thought it was pretty interesting that you could take a band that was musically the polar opposite of where it went and do so well, and then be able to come back to it again in 1989 and start up again.”

Let the Music Play also features a segment that focuses Johnston’s and Simmons’ families, including interviews with their children.  Tom says he finds it “interesting to see the kids’ point of view” on growing up around the Doobies.

Johnston says he only has one small complaint about the flick.  “The one thing that probably would’ve helped this thing a little more was some newer footage or more new footage of us playing now,” he suggests.  “Other than that, it’s pretty inclusive of everything that’s happened with the band.”

In addition to the documentary itself, the Let the Music Play DVD and Blu-ray offers a selection of archival bonus performances from various periods in the band’s history.

The current Doobie Brothers, meanwhile, are slated to return to the road next month.  They’ll kick off their 2013 tour itinerary with a February 15 concert in Concho, Oklahoma.

Copyright 2013 ABC News Radio