Sorry, that was in response to if anyone knows alternative youtube frontends, not really aimed at your original question. You probably just entered a youtube url. And piefed just goes ahead and matches all the links that start with youtube.com and adds this additional link to a privacy-respecting service… which unfortunately doesn’t work… But PieFed does this entirely automatically, and I believe to all links. I don’t think there’s anything for the user to change here. But PieFed should offer features which actually work, so me might want to deal with this in one form or another.