On a video disc (DVD, SVCD and VCD) you can include video clips as well as slideshow compilation. However you cannot add video clips to your slideshow compliation.
For example, on a DVD video compilation created with Nero Vision Express, my first title contains 23 picture slideshow. Then i have 2 video clips (2 titles each) and then for my 4th title, i have another picture slideshow. When played in order, it will seem that the video clips are in the middle of a slideshow. Transitioning from title to title will create the illusion that it is one slideshow with video clips inserted.