Time saver after a few stops did continue after restarting. Did get them all eventually.

Only one that worked after around 6 years of searching for something like this every other year or so. Sometimes YouTube needs a rest for a few hours before you can do it again, but finally clared my 4500 video watch later playlist in a few hours. Great work!

deleted my 2k video playlist in about 10mins :)

It works, I just removed 600 unwatched videos. Go to https://www.youtube.com/playlist?list=WL and start the plugin. Try it multiple times, sometimes is throws an error.