The Wall (1982)
Roger Waters wrote the screenplay for this 1982 film adaptation of the album/rock opera. Mixing live action and animation, the film tells the story of Pink and the metaphorical wall behind which he progressively isolates himself. The reviews were generally not great; most found it visually overwhelming. But the film had a few fans, even one old guy: Chicago Sun-Times critic Roger Ebert.
Pink Floyd: Live at Pompeii (1974)
There are plenty of Pink Floyd concert films but this may be the best. The ruins provide a powerful setting for the band just before it hits it mega-stride with Dark Side of the Moon. But stick to the original—avoid the Director's cut.