Greasy Fork is available in English.
Resize the video player for various sites to the window size.
< Resize Video To Window Size 피드백
Youtube has it's own script since it loads pages without a full refresh, which complicates the code. Youtube also needs to handle a bunch of edge cases, making the script super long.
https://greasyfork.org/en/scripts/811-resize-yt-to-window-size
Request for youtube
The script is absolutely awesome, thank you for developing it. I have a small request though, would it be possible to also make it work for YouTube?