Just putting this out there for people having trouble with local files. This was a change by Firefox and it can be fixed.

Go to the add-ons page (about:addons or ctrl+shift+a), click Extensions on the left, find Video Speed Controller on the list, click the 3 dots, Manage, click the "Permissions and data" tab at the top, and toggle "Access local files on your computer". This works for a lot of other addons that recently broke for local files.

Doesn't work on local media files anymore?

I love focused extensions with a clear purpose like this.

Because I'm slightly paranoid I did a quick check of the source of v0.6.3.3. The code is minimal and clean, without any wasteful bells and whistles, and doesn't do anything else than the thing it promised to do.

I should note that it has not been updated in 5 years at this point. I personally consider that a *good* thing because that suggests I don't have to worry about unexpected changes or functionality being taken away. It also means the extension predates vibecoded slop, which is a bonus. On the other hand, there are quite a few open issues on the github tracker, and if you run into one of them it's unlikely to be fixed, so YMMV.

But in my use-case (desktop browser) it works very well.

100% worth it and works seemlessly

need a patch for changing playback speed with mouse scroll

It's a fork that is not maintained anymore.

Let's me speed up a long YouTube video so I can watch it faster. Reload the page you want to use it with in case you don't see it.

This was amazing several years ago, but starting to break down because original author (codebicycle) no longer has time to maintain. I've switched to Speeder, which is a revival of this original.

Works flawlessly for me. I run Firefox on Ubuntu. It also worked well for me on Windows and Firefox before I switched to Linux.

I absolutely love this addon/extension for Chrome, but when added to Firefox, MANY features of Firefox have become unusable. Even things like ctr+f to find text, maybe options that are available when you right click a page on your mouse. PLEASE FIX!

I can't speak to how it works on other sites, but my teacher added additional videos to a Canvas post that had no ability to fast forward and this is saving me. It can be a bit janky but it's nothing I didn't expect from an extension adding a non-native feature. (Though, edit, the clunkiness went away once I used the keyboard shortcuts!)

Works, but really slows down loading on certain websites (like Reddit) making them annoying to use. Will be uninstalling.

perfect

Seems to work good most of the time; but on Youtube, sometimes it will be unresponsive, so I can't change the speed of the video. I have tried disabling all adblockers in case they were interfering, but they don't seem to be the problem. This has only occurred on Youtube so far.