I am the author of the tutorial. I created a tool that captures keystrokes and file operations in a popular editor and allows them to be played back in a browser. The author can then add a narrative as the code evolves with text, pictures, and videos.
I have more 'books' on C++, python, SQL, web dev, dart/flutter, clojure, ruby, and more:
I use these for the programming-focused cs courses that I teach instead of having the students buy bloated textbooks. The students prefer them to books (no surprise) and videos (somewhat surprising). The code is searchable and copy/pasteable so the students actually use it.
The tool is free and open.
This is such a cool tool - I worked in coding education and always loved tools that let you playback/annotate code.
Thanks for posting!
I've found it's always more worthwhile to debate and work with people who have to consistently match their predictions against reality. In my life, that's been engineers that ship and money managers who tracked against a benchmark. Everyone else I'm happy to let them have the comforts of their opinions.