You could use a Viewport node with a child VideoPlayer node as the child, and then use the ViewportTexture from the Viewport node as the albedo texture for the cube. As long as the cube has UV maps correctly setup, setting the ViewportTexture as the albedo should show the video on the cube.
This tutorial on the Godot documentation shows how to use a Viewport as a texture for a sphere, which may be helpful.
I don't know if it would work, but that is what I would look into.
(Side note: Welcome to the forums!)
