Check out an example, at least, of it here:
https://amazon.com/gp/aw/d/B071HW421...40_FMwebp_QL65.
These books have art, animation, or video that you can switch on or off.
The above referenced book with Kindle in Motion is apparently available for only the price of the Whispersync deal, which in this case is only $2.98 ($0.99-ebook + $1.99-Kindle in Motion Add-On). This book was included in today's new slate of Kindle exclusives on sale.