To download you tube, no ads on needed from mozilla Firefox..

play youtube vidio from your mozzila. you already download it,... just open C:/

then open Document an setting, then open user that you signing in , open local setting, then open application data, then open Mozzila, than open Firefox, then open profiles, then open paqs254u.default then open cache, then looking up for the file that with the big size, rename it with extention ".flv" ...

ex : C:\Documents and Settings\Hellbe\Local Settings\Application Data\Mozilla\Firefox\Profiles\paqs254u.default\Cache\

note.. you neen to unhide folder hidden. setting it on folder option .. check list the show hidden file option and show extention option.