I’m on the Tumbleweed KDE. The extension worked fine when I was using Tumbleweed Gnome. However, after switching to KDE, the extension only opened the main app, but won’t go to the YouTube link that it’s trying to direct to.
The developer of the extension said they were using Kubuntu LTS and the extension worked fine. Also, I have tried both Firefox and Chromium and they behaved the same. So I guess it might be an OpenSUSE specific issue?