One of the limitations to WSN's lightbox slideshow feature has been that it only worked manually. Now, as of 9.2.40 Beta 3, I've added a play/pause button. Look to the left of the slide title. Click play and it'll start flipping through the images automatically, then press the pause button (which appears in the location of the play button when play has been pressed) to stop.

Want to change how long it pauses between images? Go to Admin -> Settings -> Files -> Slideshow Pause.

Want to make slideshows autoplay until someone presses pause? Use the new Admin -> Settings -> Files -> Slideshow Autoplay? option.