I have a few suggestions for you on your landing page.
First, let me say that your sales copy suffers from vagueness. Vague, or non-specific, a copy is a proven conversion killer. It’s a common mistake that we often see on landing pages created by unseasoned marketers. Sure, folks can get a general idea of what your book is about, but that is the problem, it is just a bit too general.
Buyers will want to know how many pages the book has, table of contents or at least a partial list of things that are discussed in the book. The more specific you are about what topics are covered and which specific issues the book deals with the more comfortable they will be in making a purchase.
To be fair, there are some specifics in your copy, but it starts off very general at first, and I bet many visitors are hitting the back button long before they get that far into your sales copy. Try removing all the statements that are somewhat vague in nature, as some people will quit reading after just a couple of such statements.
Having videos can be helpful, but they can also be conversion killers. Be sure to test each video for its effect on conversions. I like your first video that is included in the hero unit, however, it will take folks quite a while to view all of the videos on your landing page, I’m sure there is a limit of how many videos you can include on a landing page before it harms, rather than helps conversions. Try removing all content, except the bare minimum, and test it against versions that gradually add each element back into the mix. make sure that each added element helps conversions, else exclude it.
A key concept for effective marketing campaigns is market segmentation. Since you can have as many landing pages as you like on your website, why not implement a market segmentation strategy to, not only improve conversion rates but also to identify the hottest segments and focus your landing page copy and resources on those market segments.
Your Amazon page has some positive reviews, why not include some of those reviews on your landing pages? By the way, I am not convinced your amazon reviews are all from objective reviewers, as there are no negatives. Real reviewers will at least occasionally comment on writing style or something that they did not like, along with what they did like. Whenever I see a dozen reviews without a single critique I find that less than credible.
By the way, I found your sales copy on Amazon to be much better than what you have done on your own website, Why not use the same techniques that you have used on your Amazon page? Use that copy as a baseline and test all of your new versions against that sales copy.
Another thing I have found from the previous testing is that calling your product a “book”, rather than an “ebook”, can often lift conversion rates. I am not suggesting that you mislead folks into thinking they will get a printed book, just call it a book that can be “instantly downloaded”. Naturally, this is something you want to test and verify, as not all niches will respond the same way.
There are many more small details that I could point out, but start with those big things first.