Raymond Puzio --- A Gentle Introduction to Synthetic Differential Geometry - Part 1.

Whole-channel inclusion: The New York City Category Theory Seminar is an honest teaching channel (title sample + 3 transcripts read: All three transcripts are genuine expert academic seminar lectures with structured mathematical exposition, consistent with the whole-channel verdict.); this title passed a strict title check (sonnet) after a labelling pass.

A 74-minute video from The New York City Category Theory Seminar: “Raymond Puzio --- A Gentle Introduction to Synthetic Differential Geometry - Part 1.”.

Video by The New York City Category Theory Seminar, played through YouTube's embedded player.