First thing I noticed was that you are using the Video Item instead of the Video Widget. I would strongly suggest using the Video Widget at https://apps.risevision.com to add videos to your Presentation.
Another thing is when I try to access any of your videos, I get this:
That is why you are getting nothing showing, because the video item cannot access the file. If you were using the Video Widget, an appropriate error message would be on the Display.