To extract the video ID's from a Youtube playlist:
- Navigate to the playlist page
- Scroll to the very bottom so that *all* videos are loaded
- Open the browser console (F12, then select the Console tab)
- Run the below code
- Copy the output from the console

function getVids(){let els=document.getElementsByClassName('style-scope ytd-item-section-renderer')[4].getElementsByClassName('yt-simple-endpoint style-scope ytd-playlist-video-renderer');let videoList=[];for(let el of els){let vInd=el.href.indexOf('v=');videoList.push(el.href.substring(vInd+2,vInd+13));}console.log(videoList.join(','));}getVids();

Please let me know if you can't get this to work.