A book trailer by definition is visual. What do you do when the book has few or no illustrations? The trailer linked below shows how images from other sources can be used in this case. Note that none of the images is shown in its entirety and that panning is used for each one. HOWEVER, although the images are attributed at the end, only partial addresses are provided. It is not possible to find the images at the addresses shown; a search of the site has to be made in each case.
You may use other images in your book trailers IF: (1) you have the RIGHT to use the image; and (2) you provide ATTRIBUTION (authorship, provenance, date, or location) for the image.
The easiest way to ensure you have the right to use an image is to use images that are in the public domain or are available under a Creative Commons license.
You also have the right to use images that you have changed (transformed) in some way so that the image is not identical to the original. That is, your changed image could not be downloaded and passed off as the original. A cropped image and an image panned from side to side are two examples of acceptable transformed images.