You can export a Motion Book as a "play-through" video.
Encoding a Motion Book as a video can take quite a bit more time than simply encoding the Motion Book for mobile or web.
Because of this, we recommend that you use the web/mobile formats to proofread and test your Motion Book.
When it is finished, then go ahead and select the "Video" option for the next upload.
You can simulate the timing of a playthrough video in the Motion Book Tool by toggling the "Play through mode" in the transport:
This will auto-advance your sequence, duplicating the timing that will be in the video encode.
Do as much testing and fine-tuning within the Motion Book tool, page by page. When you like how the pages are working, go ahead and upload a mobile or web version.
When everything looks good in the tool, and in the mobile/web version, then go ahead and encode a video.
If you want to really fine-tune a page, one helpful hint is to create a project with just a single page, and encode that single page as a video. Encoding a single page as a video will take substantially less time than encoding a full project with multiple pages.