My first thoughts when I saw the one for a Maximum Ride book were, first, what on earth is this, and second, if they wanted to advertise it on video why not just make a movie out of it? I know, thirty seconds is a lot easier to do than two and a half hours, but I never thought of books as a "visual" media. By giving a character a face, I felt that it took away all the excitement of trying to picture him/her for yourself. And yes, I know a lot of books give characters a face with their covers and possibly inside art, but I never found that to be inhibiting, while for some reason the visual on the screen stays with me more.
Some trailers are simply scenery shots, with shadowy figures and other such nonsense, usually the mystery ones. I can kind of get that, since they don't really show anyone, but again, if I know it's a mystery why do I need to see a trailer to know whether I'm going to like it?
Movie trailers are certainly an interesting and biased media, considering how much I loved the trailers for John Carter and hated the movie (this is not an uncommon occurrence). I've heard a lot of people even saying that Frozen was marketed completely wrong with the trailers, and it's actually a great movie even though the trailers make it look pretty, well, dumb. I haven't seen it yet, so I'll reserve judgment.
But if that's the case for movies, how could a book trailer possibly help someone who wants to pick out a book to read? All it's going to do is tell you the plot, right? And maybe make it look exciting. I don't really get it. To me, there's nothing more a book trailer can do for me that the synopsis can't (unless the synopsis is two sentences long telling me only "You'll love this book because it's a great story about love and blah blah. And it's a mystery." I've seen those before and thought it was dumb). And if I wanted to watch the book, I'd wait for the movie, right?
At this point in my book searching, I don't watch the trailers or pay attention to the photos people post in their reviews of stars they say "are" the characters. This happens a lot on Goodreads. I rarely read past the first few lines of a review either, unless I'm specifically looking for a reason (not) to read a book. The synopsis does it for me (and sometimes - okay, a lot of the time - the cover). Book trailer? No thanks.