Audio pitch down on embedded video links persists for Ubuntu 18.04. There is an XPI fix in the github reported issues, but has not been implemented into this add on. Please fix this.

no longer working

I tried it and it just doesn't work. Reloaded FF, after clearing out cache, history etc, still nothing. Tried removing this extension, repeated clearing the cache, then using the extension again, to no avail. If it's working for other/you perhaps a troubleshooting process or step-by-step walk through would be helpful?