Error console reports "ss.addRule is not a function" on line 46.
Googled, and found this describes the proper use of addRule() and, insertRule():
Just what I needed - a simple download with all the quality options. Thank you for the great work!
It works just as it's advertised. I prefer these sorts of scripts to be unobtrusive and that's exactly what this one is. It simply adds the download button from which you can choose your format.