Greasy Fork is available in English.
YouTube Center contains all kind of different useful functions which makes your visit on YouTube much more entertaining.
author of Youtubbe center has a github with it btw.
^^ latest version of my writing this is 2.1.5
You guys can download the last official version of the author, named Youtube Center Developer Build, from his Github's page:
https://github.com/YePpHa/YouTubeCenter/raw/master/dist/YouTubeCenter.user.js
Thanks for the updated link!
Newer Version
I am moving away from UserScripts.org since 9/10 of the time, OK let me rephrase 999/1000 of the time, it is down on both port 80 and port 8080. I was hunting down all my old scripts that I use. I found this and when I clicked install I noticed the "installed: 2.1.0" vs. "version: 2.0.1". So I have a more recent version of the script if you want it.