Adding video clips to a slideshow in Preview

I'm preparing a talk with a slideshow where I need to be able to show a slide as I talk. I can't do that using iMovie or preparing a slideshow using Photos which is where my photos are kept. So I'm using Preview. If possible I would like to add a few video clips to the slideshow but Preview doesn't seem to allow that. Does anyone know if I can somehow add a few video clips but still retain the ability to show them as I progress through my talk? If so , how?