I do understand that the iteration of such a multimedia book using the app could only be sold through Apple, if for sale, or be distributed for free (though you could, of course, re-purpose the plain text into a conventional ePub format).

Doug

There are lots and lots of options for creating ePubs. Even Apple’s Pages will output to ePub. Use those options for ePub.

iBooks Author is also NOT a writing tool. It is a PUBLISHING tool.

You do your writing in your favorite tool – such as Scrivener or Microsoft Word, etc. etc. You create your interactivity, photos, video, and other multimedia in your favorite tools – e.g. Photoshop, Flux, BBEdit, etc.

You then transfer the content and package it using your favorite output tool – e.g. iBooks Author for the iBooks Store, an ePub tool for your ePub book store, a Kindle tool for the Kindle Store, Microsoft Word or Adobe Acrobat for printed books, Adobe Acrobat for PDFs, etc. etc. etc.

iBooks Author is a PUBLISHING TOOL, not a writing tool. It is similar to Adobe Acrobat as a PDF publishing tool. You don’t write in Acrobat. You use Acrobat to create the finished product.