Doesn't work in private browsing even when set to allow in private.

The Extension is working just perfect, but when you restart your browser ( mozilla firefox ) the extension vanish ( its still installed, but not working ).

I wanted to get rid of every video made after 2009 but the damn thing only lets me get rid of videos made a number of days ago, and that number doesn't go up by 1 every day. Meaning after 1 day of use, I have to manually add 1 to the counter every day for the rest of my life. I dont wanna do that. JUST GIMMIE AN EXTENSION THAT SHOWS ME VIDEOS WITHIN A CERTAIN DATE RANGE FOR GOD'S SAKE!!!