As for site compatibility, there's issues where CDN (content delivery network) has strict CSP.
CSP denies any extension from accessing the hosted resource.
The extra permission is necessary to see iframes (content loaded from a different site in a frame within the current site).
You can view the code, it doesn't see any information it just accesses the html audio/video and doesn't have any outgoing code, it just accesses the tab checks for audio then uses a js to check iframes for audio.
I've been trying to figure a way for firefox to not load the extension on certain sites but its not working it has only worked within chromium.... So site compatibility has been getting worse.