ADS : Vol 1 : Chapter 8.5 : The Cusp & Pitchfork

From a channel Lumen includes in full: Prof Ghrist (Robert Ghrist, University of Pennsylvania) teaches calculus, linear algebra and applied topology with distinctive hand-drawn animated lectures.

A 5-minute video from Prof Ghrist Math's catalogue; the title names its topic.

Video by Prof Ghrist Math, played through YouTube's embedded player.