Any documentary on the Band is inevitably going to play like a supplement to “The Last Waltz” (1978), Martin Scorsese’s extraordinary record of the complete group’s final gig — or, as the guitarist-songwriter Robbie Robertson describes it in “Once Were Brothers: Robbie Robertson and the Band,” the beginning of a hiatus after which “everybody just forgot to come back.”

This new documentary, from the Canadian director Daniel Roher, seems to recognize that it falls heavily within the Scorsese film’s shadow; Roher even uses the performance of “The Night They Drove Old Dixie Down” from “The Last Waltz” for a finale. (Scorsese, who has an executive producer credit, is among the starry interviewees, who also include Bruce Springsteen and Eric Clapton.)

“Once Were Brothers” centers on Robertson, one of the Band’s two surviving original members (along with the keyboardist-saxophonist Garth Hudson), and it is a good primer on the group’s formation, influences and rise. You’ll hear about the musicians’ performances with the rockabilly singer Ronnie Hawkins; their stint playing backup — and getting booed for it — with Bob Dylan; the atmosphere of freedom at the big pink house where they collaborated near Woodstock, N.Y.; and a dive into drugs and alcohol. That last phase, as relayed here, largely bypassed the family man Robertson. (“I was confused that the guys wanted to play with that fire,” he says of heroin.)