Review:
I just bought this book, and in all fairness, I think that this method is a twist of a method we all heard of called "post someone else's video and put a link in the description".
This is not necessarily a bad thing, but I calling it 'untapped' is a bit flexible with the truth.
The way this method is demonstrated is portrayed as an example, but I can't see too many other use cases for it except for it, but it could be that I'm just not creative enough.
In the end, I think that it would've been better to monetize this ebook using affiliate links and distribute it for free, like other books in the forum.