A way to rescale monitor when black bars appear?

[essiw]

Recenly I have bought a LG ultrawide monitor. This monitor is really wide, it has a 21:9 ratio. I love the monitor as it makes multi-tasking, such as working on projects, much easier. There is however one problem that I encountered. While the screen is ultrawide, not all videos (including youtube but also sometimes downloads) are ultrawide. In the sense that they have black bars above and under the video (resulting in having black bars all around the video). I was wondering whether there is a script or program that automatically removes black bars, and thus rescales my monitor so that it hides these bars.

 

[MC6800]

Zooming automatically would be nice, but quite difficult to do reliably I would think. You should however be able to manually zoom in using Command-Option-=.