Breaks Youtube in Firefox. Was constantly getting error messages. Could not watch a single Youtube video for months now. Totally frustrated, I went on a quest to learn how to troubleshoot the problem. When I disabled "Enhancer for YouTube" suddenly Youtube started working again. Every YouTube video plays just fine now that I have removed this from both Firefox and the Cliqz browser (Firefox based). Can't believe an addon that was supposed to improve YouTube performance actually broke YouTube entirely. Probably an update to Firefox that broke the addon somewhere along the way, but YouTube works just fine now that I've removed this addon, after months of having to tediously copy any video URL that I wanted to watch over to another browser. Enhancer for YouTube gone = problem solved.