It has only one issue: when playing the next video in a playlist for some reason causes the window to scroll down which leaves the top of the video hidden. This is not a minor issue and that's very unfortunate because this extension would be perfect otherwise.
EDIT 1: Reading back the review several users reported the same issue, some over a year ago.
EDIT 2: Workaround by commenting the scrollTo function in ythd.js and disabling auto-update.

please add rutube support!!!

Está extensão é muito boa, pena que não está recebendo atualização. Bem que podia ter a melhoria no aspecto de resolução de tela para se adequar ao Firefox para Android, se possível receber novas funções e também opções de escolher o idioma de localidade do usuário na extensão, que nem os concorrentes 'Enhancer for Youtube™' e 'ImprovedTube!' .

Installed it on Firefox on Android and it failed to stop autoplay. I did set it to auto pause everywhere I could, but it didn't work.

Ok

Unreasonable permissions concerning user data completely unrelated to what it's supposed to do.
Worked just fine until it asked for access it doesn't need to function (Access your data for all websites).

Hope no one install that trash.

Merveilleux