Not to criticize the guide, it's brilliant! If asked for improvements, I'd suggest adding a table of contents.

Slightly off topic, but the guide does suggests reading time. It's interesting that people keep using read estimates for technical/scientific/professional documentation. This one says it's a 58 minute read. Not 1 hour, not 59 minutes, but spot on 58 minutes.

Now, I'm not a novice in using ffmpeg and I think I'm at least an average person. I can tell you that it would take me a _lot_ longer to read this guide in a meaningful manner.

But, a brilliant guide. I'm definitely going to use it to expand my ffmpeg knowledge.