I don't usually write reviews for add-ons... But this one is PHENOMENAL! Not only does it d/load YouTube vids, it will take that same vid, rip out the audo only and save it to your hard drive! For us Old [Fart] School audiophiles who still like to burn CDs, this extension is a Godsend! It is simple to use, but there is an add-on to the add-on necessary for its proper operation, the installation of which is a little dicey. All-in-all, I will use this add-on forever... Or until YouTube or Firefox decide it works too well and remove it from their collections.