It does what it promises, but it literally makes watching videos impossible without a Massive lag that reduces the quality of the video and doesn't let me interact with ANY button in the player, it just ruins the video experience, i reinstalled firefox multiple times and even when i installed another OS the issue still happened, without me knowing that it was this add-on who was causing the issue, although this is a great extension that does what it promises, i still want to watch videos without a massive delay y'know :/