Very, very useful. One aspect I would like though is being able to use the modifications to videos and that they would be applied when downloading the video.

ここまで素晴らしい機能補完は見たことがない

Fantastic add-on that works, has useful features and simple to use.

Muda totalmente a forma de assistir vídeos. Facilita a vida, mesmo para assinantes do serviço premium do youtube.
Só uma coisa que eu sinto falta: logo no começo, nos controles do player, para cada ícone aparece um "i', que mostra uma pequena explicação do comando. Esse recurso é bem útil e não aparece nos controles de volume.

great addon for youtube experience with tweaks .whole family uses

Frequent updates, developing in the right direction. Many useful features, lots of customisability.

Install it, customize it, and forget about it. You'll come to think that how you have it setup is just how Youtube is supposed to be - whether it be colors/looks or functionality. The auto-theater mode, however, is my favorite feature, followed closely by the speed controls. Never had an issue or conflict with Youtube or Firefox.

Very good to hide YouTube's unnecessary parts—watch the video directly, without related videos or any other visual distractions designed to keep you there all day without noticing.