You can contact the developer of the Videodownload Helper extension if there is a problem with that

You can contact the developer of the Videodownload Helper extension if there is a problem with that extension or if you want to make suggestions.

https://addons.mozilla.org/firefox/addon/video-downloadhelper/

http://forum.downloadhelper.net/forum/3

You may have to wait until the next week start because this forum is usually not online during weekends.