The bonus material is a chapter called "The Making of a Hypnotist", which was cut out of the final version of the book. It's a 9-page PDF file about hypnosis that you can download.
If you want to read this chapter, you have to pre-order the book before the release date, which is October 31, tomorrow!
[Update] To redeem the free chapter, go to this blog post and enter your purchase information from Amazon, Barnes & Noble, etc.
