Twenty-five years ago, on Thanksgiving Day 1976, five thousand cheering fans gathered for the historic farewell concert of “The Band.” In Martin Scorsese’s “brilliant” (Newsweek) film, superstars Eric Clapton, Joni Mitchell, Neil Young and Van Morrison join the musicians on-stage, along with one-time collaborator Bob Dylan, and Ringo Starr in an unforgettable finale.