How to create a playlist of all videos of a channel:

Create bookmark using: javascript: location.href = document.URL  + '&list=ULzjU1d9_hv20';

1. Go to all videos of a channel.
2. Sort by Oldest to Newest or however
3. Play the first video.
4. Click the bookmarlet we created and the page should refresh to make the entire channel a playlist.

Note:

It cannot be saved as an actual playlist, so bookmark if needed.