Depending what browser you use, there are probably extensions to alter the youtube site. I use Chrome, and use this extension:
https://chrome.google.com/webstore/d...kfpphniapiiifn
It lets you choose what quality videos are displayed in, and you can hide any section of youtube you don't like (comments, recommended videos etc.) I'm just not sure how it handles playlists, I haven't used one since I started using this.