I'm not a big fan of video previews of books. Some of the simple, home-grown, made-on-a-shoestring videos are enjoyable and have a certain arty flavor, but most of the professionally rendered book trailers are simply awful, and make me want to steer as far from the book as possible.
There was always one exception in my mind--the book trailer a group of Italian film students did for Neil Gaiman's Coraline. It is slickly done but imaginative and intriguing. Perhaps there are other gorgeous trailers out there; since I don't spend a lot of time looking for them, I may have missed out.
But with the Spanish trailer for Testament that Alis Hawkins just announced, I'll have to amend my former judgement. There are at least two marvelous professional book trailers out there.
Odd that the two I like are rendered in Italian and Spanish, respectively. Is it a Mediterranean medium?