Hi,
I notice there is the conflict of mesh between the original cube and the array of the building floor. But I don't see this in your video. May I know why?
That's called "Z fighting" and it happens when mesh planes are occupying the exact same plane in 3D space. It must have been happening in the video too BUT (when I scrubbed through) I mainly used wireframe and flat-shaded mode which doesn't appear to show the z-fighting by nature.