If the add-on isn't working for you, try these steps
The add-on isn't working/stopped working
This is for when you're suddenly back to new twitter or never got back to old twitter. For other issues check known issues below or submit a new issue.
First, try hard refreshing twitter. Shift+Click on reload in the twitter tab.
If that didn't work, try reinstalling goodtwitter by going to the store page, clicking remove then installing it again.
You can also try restarting chrome or your computer.
If all that didn't work create an issue on GitHub here
Videos/GIFs are not loading
Videos are Pitched down
No fix yet. Issue #6.