Just installed and so far so good. Just what I needed.
Then I checked some negative reviews in this page and I couldn't verify that those guys maybe have some virus in their computers. Any way, I will continue using it and will post if something goes wrong.

Does what it needs to do.

Excellent. Thanks a lot Ray, nice extension.

This Firefox add-on is pretty good! Ignore those people who are saying, "It doesn't work." I used this Add-on on Firefox so I could fasten. I promised that I would quit YouTube until Lent is finished. So this really helped me keep my promise!

Very good extension previously but now no longer works.

Used to be amazing but recently stopped working

Much more simplier UI, than other blockers. Really nice, helpful.

used to work some (long) time ago, now it doesn't

Works perfectly, simple and easy to use. The only downside being that when you have for example, 10 tabs with different YouTube URLs and then you want to block YouTube, all the tabs lose their url and become YouTube, which means that after unblocking YouTube, all my saved tabs become the default main page.

DON`T USE THIS PLUGIN EVER! I had to report it.
When you have websites blocked, this plugin ruins all those tabs you have opened. it does not only forbid access temporarly, it corrupts the entire tab so it will never be accesivble again!

Also, the Ad-On is very unintuitive. but the main problem is that it will destroy your tabs.

Mozilla Firefox should not allow such a plugin.

Almost impossible to use and block sites

好用

The extension works great! took a bit to get used to but after messing around, I was able to get the customize the rules to my need. One thing I would like is a way to block some sites all the time and some on a schedule.