How to add Downthemall button to Firefox

This is a short tutorial of the issue I was having lately. This was annoying me increasingly. So this is a short solution to the problem.

Skip the chatter go to solution: https://www.youtube.com/watch?v=L_q4PwIKrDI#t=1m48s

The Problem: if you have a FLV, AVI, MP3 download link, you cant download them all. In default Firefox will just open them instead downloading them. So this is my solution using downthemall addon.

This is the direct link to this handy Firefox addon:
https://addons.mozilla.org/en-US/firefox/addon/downthemall/