Adds an event listener on the letter `h` to toggle video overlay visibility
当前为
When focused on Crunchyroll videos, press h to toggle overlay visibility (toggles between 0 and 1 opacity). This script changes opacity and not display or visibility to still allow clicking to pause/play videos and double clicking to fullscreen videos.
This also means if you accidentally click the bottom of the video, you could click somewhere in the still active scrub-bar and jump to a different part of the current video unintentionally.