Try some of the following suggestions:
Bookwink Video Booktalks
Digital Booktalks (Created to encourage struggling readers)
This site has booktrailers organized by grade level.
They are more like movie trailers and combine images, music and a voice over to "sell the book." You can actually download the trailers and have them play in a loop on a local machine. (http://gordonslibrarylinks.blogspot.com/2010/10/creating-looping-playlist-for.html)