Book Trailers

While Googling information about Abraham Lincoln: Vampire Hunter I came across a trailer for the book. Trailers are definitely a way to promote books, but I'm surprised that the book trailers I've seen are books that I would presume would sell well as the author also wrote Pride and Prejudice and Zombies and Sense and Sensibility and Sea Monsters. Book trailers on Youtube are a great way to advertise for books. However, if the most prevalent trailers are for books from large publishing companies, the trailers are not helping to publicize otherwise little-known books.