This extension for firefox allows you to open YouTube videos from a playlist in a new tab as standalone videos without the (autoplaying) playlist.
The add-on can be built using web-ext
:
web-ext build
This creates an unsigned add-on. To build a signed version, you have to change the add-on id and submit the add-on to Mozilla Add-ons for signing.
This add-on by Klemens Schölhorn is licenced under the terms of the GPLv3.