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This script resizes the YouTube player to different sizes.

There is a resize button that allows for easy-to-use configuration of the size.

Use the shortcut key 'r' to resize the player and switch to resize mode.

Once resize mode is activated:
Use the 'z' key to decrease video player size and the 'x' key to increase video player size.
The size can also be modified using 'Shift + Scroll' to decrease/increase video player size.

Notes:
Resizes to many sizes but not every size.
This only works on the new YouTube website layout on desktop.
Works best with the web browser maximized and default resolution.