Go to bookmarks manager and select all the YouTube links and copy and paste them in a text file, say you.list, and RUN following on your terminal (assuming you use a linux system):
grep -o 'v=.*' you....
Navigate to the URL of the playlist you want to copy.
Click on the menu button on the right (3 vertical dots).
Select "Add all to..."
Either add the videos to an existing playlist or create a new one....
For the example in the question, on Google, try something like the following:
site:youtube.com inurl:(QuqCMHe4kxQ list)
(Thanks to Annan)
site: and ...
I made an app to do exactly that, hosted on Heroku: YouTube Playlist Length. You can also find the app repository here.
Note: it can find the total length of a playlist that has up to 500 videos. If ...
You're going to need to change the privacy setting of the playlist to "Unlisted". Then you'll be able to share a URL with anyone who you want to be able to access the playlist. The playlist won't show ...