Worked until a few days ago, where Firefox is reporting that this Add-on was causing Youtube to shit the bed. It's a shame that I have to move on, both in because the thing still does work as I'm still not seeing the blacklisted youtube accounts (But I have seen some sneak through), but also because now I have to somehow upload all 422 accounts I've blacklisted onto the new add-on. @-@
I fear when I turn it off to attempt to blacklist everything again easier...