**NOTE!** Rated 5 out of 5 stars
If you have the add-on "HTTPS Everywhere" installed and it is set to give you a secure connection to youtube, then Complete YouTube Saver WILL NOT WORK!, you will need to disable the secure connection to youtube via "HTTPS Everywhere" options, once done, then manually remove the 's' from 'https' in the videos address on youtube in the address bar of your browser (if you still have the video open!), then click on the arrow to load the page and check that you now have a http connection instead of https one!, then Complete YouTube Saver should work as the author intended it to.
If you do the above, then any future pages that you open on youtube should automatically load up in http instead of https.
Thank you for the very constructive report! We had not been aware of this issue. We will be looking into making CYS HTTPS-aware, as there is no reason it cannot work, and it will offer better privacy for browsing the YT site . Truth be told, watching YT videos themselves via encrypted connection is a complete waste of CPU power (server and client). As the download link (even https) uniquely identifies videos, there is no privacy gained there.