At the moment, you can get fullscreen videos with black bars. To remove the black bars you'd need to have the slider layout scale responsively, without being fullscreen.
It might be possible to achieve this functionality if you'd use a dummy placeholder image as background to make sure you keep the image always centered and having the video as an overlay spanning
100% width and
100% height, but it's not something I have tried.
Your idea, however, is interesting and might be a good idea for an update.
Thank you very much for your interest!