Plugin already installed .
Thanks for help !
Thank you for writing us.
Please go to the FireFox main menu Tools | Extensions dialog. Locate MetaProducts Integration plug-in. What is its version number?
You can install the recent version from: http://www.metaproducts.com/download/mpint.xpi
it's the latest one. Version 1.2.5
trying to solve the problem I figured out that the Zonealarm plugin blocked the context menu of Mass Downloader.
Deinstalled it and now i can see again the context menu : Mass Downloader > Download all
Thanks anyway for your help
Thank you for your feedback.