How to create a video for a map?

So, I started figuring it out, and a question immediately arose. How do I choose my map as a backdrop if the list only contains some random stuff?

I don't create my map in advance. In the dialogue creation menu, in the map selection section, there are two buttons: "..." and "new". Apparently, your screenshot shows the result of pressing the first one. I press the second one, and then everything becomes straightforward.