Here are a few videos and introducing iBooks Author and also some that explain how the convert video content into the right format:
http://www.mequoda.com/articles/online-publishing/two-things-you-need-to-know-about-using-audio-video-in-ibooks/
https://discussions.apple.com/thread/3675922?start=0&tstart=0
https://discussions.apple.com/thread/3677693?start=0&tstart=0
iBooks Author Tutorials
