What exactly is a DVD slide show?

That's a very good question, and I'm glad you asked.
The short answer is that it is a movie made up of images that we have scanned from your slides (or negatives). So unlike a "old fashioned" slide show you don't have to click a button to view the next slide, the next slide will automatically be shown after 5 seconds. If you want to spend longer with a particular image simply use the Pause button of your remote control.