Cool YouTube Darkness
Apparently Google is working on a not-so-secret Dark Mode for YouTube and you can activate it yourself in just three easy steps. Personally, I find a darker background to be easier on the eyes and certainly hope that Google incorporate this feature into YouTube on a permanent basis.
How to Activate Dark Mode
Open a YouTube page, hit CTRL + SHIFT + I or F12 to bring up the development window on the right hand side of the page (or at the bottom, depending on your browser), select the CONSOLE TAB if it isn’t already selected , then copy and paste this text into the console:
“VISITOR_INFO1_LIVE=fPQ4jCL6EiE”, without the quotes.
Close the developer window by clicking the cross at the top right and then refresh your browser by hitting the F5 Key. Then click your account icon (top right) in YouTube and a Drop-down menu will appear with Dark Mode added as an option.
With that option now available you can toggle Dark Mode on and off.
I’ve tested this method with Chrome, Firefox, Opera and Edge with no problems. It’s also worth pointing out that the console command, in my case anyway, appears to make the Dark Mode option always available on future YouTube visits in new browsing sessions.