All I am looking for now is a way to add an item to the right click menu on Firefox to open a video with mpv. This way, I can give my relatives an easy to understand procedure for watching videos without eye cancer.
StopTheMadnessPro is a browser plugin that can skip YouTube ads
Peertube supports importing from YouTube if I recall.
Right, but I want a two-click solution from vanilla youtube, because it is not for me; it is for non-technical relatives. For myself I just open everything through mpv anyway.