When downgrading to version 0.94 (the one that actually still works) remember to:
1. remove version 1.0.9 found in Firefox extensions:
type "about:addons" in the top address/search bar
2. download the old version 0.94
https://addons.mozilla.org/en-CA/firefox/addon/youtube_downloader_webx/versions/
3. disable automatic updates

Otherwise Firefox will "upgrade" it to 1.0.9 and this extension will stop working!

The 0.94 version sorta sucks since you cannot rename the files prior to downloading, only after so you mus wait if it is a huge video file.