Related to your previous request:
I think this will be an unpopular suggestion. But I am interested to hear what the community says.
Can you expand further on how this would work so we can understand your use case better?
For example, if the Video Mode is set to 1920x1080, and you import a video that is 1280x720, you are saying that you want the imported video to NOT fill the screen. So how should it appear? Should it be centered with a black border all around it? Or maybe it should be in the upper left with black bars on the right and bottom to fill the rest of the space?