This is what they say:
"I'm sorry about the previous misunderstanding.
Currently, Kindle Edition with Audio/Video content is supported and available on Kindle Fire (2nd generation), Kindle Fire HD, iPad, iPhone, and iPod Touch. Kindle e Ink devices do not support Kindle Editions with Audio/Video.
KF8 features are not currently supported in Kindle Edition with Audio/Video content. The file delivered to Amazon should be a Mobi 7 EPUB with self-contained audio and video or a Mobi 7 .prc file with self-contained audio and video. (If delivering a .prc, make sure the file was created using the latest version of KindleGen available from
www.amazon.com/kindleformat).
Please see section 6 in the Kindle Publishing Guideline for more details on how to do so."