Mutes / unmutes a YouTube video / Shorts by clicking the middle mouse button within the video player. For Shorts you can also middle mouse click the black side bars around the video. While performing the middle mouse button click, the scroll button gets disabled. Mute / unmute / scroll disabling won't work with any elements floating over the video player.
It seems this script stopped working due to YouTube's recent specification changes.
This script is quite important to me, so I'm waiting for an update.