Hi all,
just for latecomers to the course such as myself, the “E” shortcut used in this lecture is to create a “new cut”, however in newer versions of Blender (I’m using version 3.2.2) that key is now RMB.
And since I’ve gone through the rounds of making a post on this, here is the official documentation for anyone interested in more shortcuts/usages for the knife tool:
https://docs.blender.org/manual/en/latest/modeling/meshes/tools/knife.html