Rated 4 out of 5 stars
I think there's a new bug with filenaming in 0.0.0.5. It looks like the last character is always cut with all youtube videos.This review is for a previous version of the add-on (0.0.0.3.1-signed.1-signed). This user has other reviews of this add-on.
try it https://addons.mozilla.org/firefox/downloads/file/200746/youtube_tools-0.0.0.6-fx.xpi?src=devhub