This would appeal to me more if I didn't get visions of people watching the 60 second videos and claiming to have "read" the book (my inner bookworm is cringing).
If you can have previews for movies, though, I don't see why you couldn't have previews for a book, assuming that's how they are actually used (because I'm sure we all know how Cliff's Notes and even literary Wikipedia entries have turned out so far; some people do legitimately use them to merely clarify the text, but far more use them as a substitute...).