The optimization routine in iBooks Author 2.0 is well intendtioned but the execution of those intentions is quite poor. In addition to bloating the size of your videos and, hence, your iBook, it can also degrade visual quality in dramatic fashion. For example, I created a screencast in ScreenFlow 4.0 (just released) that looked great in QuickTime X Player (sharp, highly readable text, etc.) but in iBooks I could hardly recognize these details at full screen. Now, ScreenFlow (by Telestream) uses the X.264 CODEC which is at least as good as the H.264 CODEC that Apple uses (many video pros argue that X.264 is better). That may be a part of the problem I saw. The other factor may be that this .m4a video file was 1280x800, not the 1280x720 maximum for iPad. The IBA optimizer dutifully attempted to make it "right" but, instead made it unusable for my iBook. To be fair, tossing it a soft ball (video that already meets iPad specs in every way) produces decent looking, albeit heftier, results.
BTW, you can see the optimizer in action and thereby get a sense of the time it takes by replacing a video in an IBA project. You do that by clicking on the media to invoke the "Edit Media" button, clicking that and drag/dropping a new video in its place. You'll get a progress bar and a "time remaining" estimate. You will notice that the longer it takes, the worse the outcome in terms of file size and visual quality. My 1280x800 file took a long time. A 1280x720 .m4a file takes much less time.
It gets worse. The optimizer apparently uses the QuickTime engine which means that any tracks beyond one video track and one audio track will be trashed. Thus, if you have any soft subtitle or alternate audio tracks, they will be deleted without notice. I used a test file with three audio tracks (English, Spanish and French) and four soft subtitle tracks (English, Spanish, French and Hungarian). These extra tracks were perfectly accessible in *.ibooks files produced by iBooks Author 1.x in the iBooks.app as well as the Videos.app and elsewhere. The optimizer (ne terminator) in iBooks Author deletes all soft subtitle tracks and all but the English audio track.
Let's not forget that iBooks Author is ostensibly used by commercial textbook publishers (McGraw-Hill, Pearson et. al.) and, furthermore, that media accessibility by all students is mandated by federal law. I cannot imagine that anyone is not going to want to turn this feature off, at least until it becomes mature.
With iBooks Author 1.x, I had figured out how to create very efficient and highly capable video that IBA will accept. This "feature" throws me and a lot of other capable people into a ditch.
Apple may not care to listen to you and I but surely they will pay attention when the folks at Pearson, McGraw-Hill and other commercial entities try to work with this new version and begin to feel our pain. Let's hope that TimeMachine works as advertised.
