recently I had my windows 10 reinstalled and had to reinstall firefox before the reinstate of operating system I had a video add on for facebook that would let me save a video to my desktop so i can send to facebook or send privately in facebook chat> had an add on that did that but i can not find it anywhere. again i had forgotten the name i think it was browser downloader but not sure. I forgot the name but loved it also now after reinstalling fire fox in the setting where it says application and defaults i do not see my mp4 which is windows media player listed there. I am sending a screen shot to you