My reaction to that is bleagh! I can appreciate that Simon & Schuster is feeling business pressures to compete, and as far as nonfiction goes, I can even see some value to being able to combine instructive videos with text. The purpose of nonfiction is often to inform or even to teach, and I can see multimedia working for that purpose just fine.
But when it comes to novels, a vook is going over to the enemy. This is all very similar to the "digi-novel" that Anthony Zuiker announced a while ago. I didn't like the sound of that much, and I don't like this, either.
The way to save books is to get more people to read them, not to turn them into some kind of hybrid of books and movies. I want to watch the movie that runs in my head when I read, not one on a screen. What gets me is S&S describes the vook experience as watching videos of "key scenes." So, just when things get so tense I'm totally immersed in the story, instead of turning the (virtual) page, I'm suppose to stop and see someone else's interpretation of what's happening? No! No! No!
Why stop with key scenes? Why bother with having text? Just make a damn movie!