Extension is working in only certain tabs

I am developing an extension that will fix YouTube spacebar issue ''(after recent YouTube update after Alt Tabbing from other window, spacebar is not working to Pause/Play videos)''. The problem is that my extension is not working anywhere except on '''https://www.mozilla.org'''. I've already added "*://*.youtube.com/*" to "host_permissions" in my '''manifest.json''' file and it's displayed as '''"Can always read and change data on this site"''' on YouTube, but it does nothing. On '''https://www.mozilla.org''' my extension is activating properly (writes test message in console). I added my extension on "about:debugging". Can it be related with that? Appreciate any help!