A speedy addon for firefox (extension for chrome ) that injects custom grey-ish css in your page when you're roaming on youtube.

Get it from https://addons.mozilla.org/en-US/firefox/addon/dark-youtube-theme

or: https://chrome.google.com/webstore/detail/dark-youtube-theme/djhcepodfooinnfhfccmoeabagbjchhg

Disclaimer:

I got that main icon from https://www.iconfinder.com/icons/104445/video_youtube_icon, it was created by Picons.me and it's free for commercial use.

I got the puppy eyes icon from http://thenounproject.com/term/puppy-eyes/30086/, it was created by Joe Shelton and it's licensed under CC Attribution 3.0 (CC BY 4.0)