There are a few issues you need to resolve. First, the timeline of the slide and the timeline of the media/video are not correlated. You will need to pause the media before going anywhere. Then you would have to trigger it to play when returning from there. You could set it up to lighbox the question. I have attached an adjusted version of your example. I added a variable as a switch. This variable is a true false trigger, but you could probably make it numbers that would trigger additional lightbox questions and then return to play the video.
