An inexpensive but massively comprehensive manual covering all aspects of making and using video "trailers" of "previews" for marketing books on the internet...easily, and for free.
Covers free programs for video and audio, none requiring special skills. Sources for obtaining support and help, video clips, artwork, sound effects, and music free on the internet, then producing a video and utilizing for promotion.
Slanted specifically towards authors, not video makers.
Six dollars from adoroworks.com