How does it work?
I know it's only available to read online, but why? Can it be converted to pdf? Does it include videos? How is the book organized?
It isn't available in a PDF presumably so that it can't be stolen, its only available online through the website or through an android app,iOS, etc etc. The majority of it is based on song layout clips from the website, they analyze popular songs and their chord progressions, the clips are all videos of songs that people put on the website (the normal free version of the site where u can look up a song and see it's melody and chord progression). It walks you through those and analyzes the melody and progression. The "book" is primarily about this, it doesn't really introduce any complex theory or go deeply into the modes. After teaching you how to construct major and minor scales It teaches you popular chord tendencies such as how the root acts as home base, ending on V or IV (cadence), and how notes in the melody can create dissonance or consonance with the underlying chords. It does a great job of explaining everything they teach you with a clip example right after, I just wish it taught more material.