To extract all the video IDs from a YouTube playlist. Open the playlist page, scroll down to the bottom, click load more, repeat until the end, then open Console and paste this code. Output is a list of video IDs from the page.

youtube-extract-ids-from-playlist.js

var els = document.getElementsByClassName('pl-video');

for(i = 0; i < els.length; i++) {
	var el = els[i];
	if(el) {
		var src = el.getElementsByClassName('yt-thumb-clip')[0].getElementsByTagName('img')[0].src;
		if(!src.match(/\.com\/vi\//g)) { continue; }
		var id = src.split('.com/vi/')[1].split('/')[0];
		console.log(id);
	}
}

why not use yt-dlp? In a console with yt-dlp installed, execute:

yt-dlp --flat-playlist --print "%(url)s" "PLAYLIST_URL" > playlist_urls.txt

replace PLAYLIST_URL with the url and exec the cmd. This will give the entire urls in a txt file. Then in the file, simply find and replace https://www.youtube.com/watch?v= with nothing.