Just before Wayan posted, I also found out that the background with the video had to go in first. I must admit that I hadn't discovered that the actual video had a z-index of -100. I experimented with a video of my own and started from scratch with it and one of the menus, and found that it works well if the hierarchy of files and folders are like in the example here: https://eikweb.com/stuff/hierarchy.jpg .