Works for me, though it does not save on resources at all.

Just lite grey screen layer DOT NOT save energy, bandwidth neither.

it sometimes does nothing for whatever reason no matter how many times you try on the video, but when it works, it's good.

doesn't work

видео начинает заедать как будто. возвращается в моменты ранее проигранные уже.

далее, сама кнопка точнее надпись, ибо графики нет... занимает места 1,5-2 кнопок обычных. т.е. не компактно расходует место внутри плеера.

не пробовал во встроенных плеерах youtube на сторонних сайтах. но обычно там никакие расширения не подхватываются в плане дополнительных кнопок управления. всякие скриншотеры и тп в пролёте.

внешний вид кнопки поменять нельзя. настроек нет толком.
в этом плане идеально показалось(или близко к этому расширение с хрома Music Mode for YouTube™)

I've only just installed it today. I click on the icon on the url bar and the Youtube window goes black. I can still hear the music or audio. I tried to see if it reduced my bandwidth usage but I couldn't figure out definitively with the windows network monitoring tools: https://answers.microsoft.com/en-us/ie/forum/ie8-windows_other/how-can-i-monitor-download-usage-using-windows-7/6ce7c97d-d279-4130-859a-377747887684 So, I can't yet certify that it reduces bandwidth use. I choose this one of others that had more users because this one doesn't ask for permission to access data from all websites. I am afraid of apps like those - maybe they'll take my passwords. Why do they need that data if their app is only for Youtube? This one feels safer because of that.

Not sure why but it works a bit then it wont work. Have to disable and reinalble it and restart firefox for it to work again otherwise I would give it 5 stars

I like it. For youtube videos with annoying facecams. Or simply bad videos with good audio. Like music videos.