Maybe. Also, for newer videos YouTube takes a while to expose higher qualities. I see now that the videos have very few views and that only 720p is available. This could also be the reason.

> Two videos have the hum. This cannot be changed because the lecture capture system in the lecture room does not allow this (It's Panopto).

You can probably get rid of the hum pretty easily with pretty basic filtering in a video/audio program (or even a Python library). You might also be able to re-upload just the audio tracks. Just say if you want my help with this.

> The funny thing is this: Once I started doing the memory diagrams in the lecture, the students' work exhibited a lot more quality. Further, absolute beginners understand, for example, the concept of an iterator vs. iterable.

I'm not surprised. I've been saying for a while now, that learning programming is analogous to learning how to play an instrument (e.g. the piano) where you need to learn the right techniques and concepts early on if you want to be able to become highly skilled later on. Otherwise it's unlearning and relearning a bunch of stuff, which is less than optimal. Thank you for validating this idea of mine, somewhat.