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Listen to only the audio on YouTube without loading the video.
< Opinie na Youtube Audio Mode
Maybe I didn't understand your request, but at the moment the userscript already does what you ask. I mean, I didn't touch anything of that feature, I've just tried it and it works as when the audio mode is disabled.
thanks for this script. i would like the thumbnails (ytp-preview) to be shown like when you point the mouse at the progress bar (ytp-tooltip-bg) automatically to have a graphical reference.