Calculus 3, Session 23 -- Introduction to multivariable integration (iterated integrals)

From a channel Lumen includes in full: Beard Meets Calculus (Professor Butler) is raw classroom capture of complete college courses in calculus, business calculus and differential equations, with quiz and exam practice sessions.

A 49-minute video from Beard Meets Calculus's catalogue; the title names its topic.

Video by Beard Meets Calculus, played through YouTube's embedded player.