I can see what the appeal of doing video trailer is-- it's a commercial for your book! That's exciting! Of course, most of the video trailers I've seen are made with all the dynamic hook and technical skill of your average public access program. They certainly don't entice me to read the book.
I heard one person say of book trailers that the best they can do is not hurt your sales. The more of these things I see, the more I can't help but agree.
I was at a panel once where the panelists were advocating making book trailers as a promotional tool. Now, like I said, I can see its value, if it's done well. But then it was suggested that, in order to make one's trailer, one should search through photo archives of stock images, finding stuff that's out there that's free to use.
I couldn't disagree more about that. I mean, why would you use images that only kind-of, sort-of match what your book is about? Let's say, for example, your book has vampire-like and angel-like creatures. Would ANY vampire or angel pictures be suitable? Probably not. I would argue that any images (or video) that aren't specifically made for your book would look generic and unconnected. You wouldn't copy-and-paste text from some other book because it's kind of like what you want your book to be, would you? (I hope not.)
I mean, if you're going to make a book trailer to promote YOUR book, then make that trailer equally your own, just as original.