A lot of Users like to view and use software in Darks mode. Those who work at night are a big fan of Dark mode. This is the main reason why all the sites and software with heavy user base have started using dark mode.
Even Microsoft has added a Registry tweak to enable dark theme in Windows 10. Youtube Users have also been looking for dark theme since a long time. Though Youtube has not officially povided this mode to users but there is a small tweak using the developer tools of the browser by which users can activate dark theme in youtube.
Best Chrome Extensions - Dark skin for Youtube
If you are not very tech savvy, want to keep things simple and do not want to get your hands dirty with developer tools and code etc. then there is a solution for you too. The solution is a cool chrome extension called Dark skin for youtube.
This chrome extension makes it possible to view youtube in dark mode. Though this would not be the official dark mode of youtube but it would be good enough for the eyes of the users. So if you watch a lot of Youtube at night and are looking to give your eyes some rest then give this cool chrome extension a try.