I love going to movies and seeing coming attractions. It gives me a taste of films that I might be interested in seeing. Sometimes a preview announces a film I didn’t know about. Sometimes it gives me a glimpse of something I already knew about, and gets me excited about seeing it.
As a form of advertising, previews work. They aren’t intrusive, like commercials. You pay to see a movie, and previews are a sort of bonus feature. They offer content.
People like content. They like information and entertainment. They seek it out.
Books have their own kind of preview. At the end of each of my paperbacks, there is a sample chapter of one of my upcoming books. I think this is a no-brainer. The best advertising for your writing is: your writing.
He’s willing to have people put their previews at the back of his books – for a fee, of course.