I think these extensions set the standard playbackRate property on the HTML5 video element: https://developer.mozilla.org/en-US/docs/Web/API/HTMLMediaEl...
Try setting the property manually using the JavaScript console and see if you get pitch correction. If not, maybe make sure you're on the latest version of Firefox?
Re:Ask HN: How to self-learn electronics?
by Baeocystin on Monday April 09, 2018 @07:02AM
(#16791942)
I'll give that a shot. Thanks.
Does the extension you linked do pitch correction as well? I wish I could find one that does for Firefox, too, if you happen to know of one. The only playback speed control extension I've found for FF doesn't.