Make Video Resize With Window

[TangoOversway]

First, I want to be clear: With default settings, I know the video window resizes to match the size of each video it plays. I do NOT want this. I want the opposite.

When I have a window open and I'm watching something in higher quality, it may fill my window. But then, when a lower quality video comes up, it shows at its smaller size with black borders around it. In the past I've been able to resize the window and that would change the size of the video in the window. In other words, the window controlled the size of the video - the opposite of the video controlling the size of the window.

When I could do this, videos would still keep their same proportions, but they'd size to the window.

I can't figure out how to do this now, with a new install.