Great extension! The description mentions URL RegEx based black/whitelist. I only see an option to whitelist pages which confuses me on the following: Say the user wants the extension muting content by default on all but a few sites they regularly keep in the background while doing something else (for example, youtube or spotify). Is such blacklist functionality already implemented?
EDIT: Thank you, now it's clear! What exactly is the difference between enabling "Consider all windows" and leaving it unchecked?

Wonderful extension, it's exactly what I needed! Thank you.

good extension!