Good functionality, helpful and customizable shortcuts, very unobtrusive design.
However, it is prone to crashes when skipping backwards in sped up videos and would often appear to slow down pages with no videos at all. I also had the impression that turning the speed up and down didn't entirely cancel out

Can't live without it, it's simply so good.

not showing up

Very good addon fast and functional, would like an option to leave the button strip all buttons always visible

I had a bit of a difficult time leaning how this Add-On worked, but once I got the hang of it (and customized the controls to my liking), I LOVED it! It's so nice to be able to watch videos in 2x or even 3x speed almost anywhere!

useful

Request access to all data of all websites (wich includes passwords) for changing the speed of a video?. Not on my computer my friend.

Genial

One of the best add-ons out there!
Controls speed of every motion picture, even GIFs !!! It's Crazy!!
You can set your own shortcuts, so I set the same as youtube. Now I can easily speed up up to 6x or even more on youtube ! What else could you ask from a speed controller?

Seems like this extension has access to all websites on Firefox unlike on Edge and Chrome, and I don't like this. I am not sure if this is something to be blamed on Firefox or the extension, but it should not have access to all data on all websites since these types of extensions will be ran on a handful of websites. Uninstalling it now.