YouTube Center is YouTube Center comes with many features, including the ability to download videos, repeat videos, change the default quality of the video to be played by default and etc. YouTube Center is designed to look as much like YouTube's design as possible.
YouTube Center is a userscript, which has been made into an addon for Firefox, Safari, Chrome, Opera and Maxthon.
It's recommended to install the addon for your browser.
Make sure that you have Greasemonkey, Tampermonkey or Violetmonkey installed to actually be able to use the userscript version. It's is discouraged to install the userscript natively in Chrome as that makes a few features unavailable.
To install YouTube Center just click on the green button, which says "Install". You can find more information about YouTube Center on its wiki.
The Chrome addon needs to be installed by going to the extension page and dragging the Chrome addon file (.crx) into the extension page. Note that you also have to have enabled developer mode to actually be able to use the Chrome addon. Mirror: Chrome addon
If you want YouTube Center to be in your language and are able to translate it from a language YouTube Center supports to your language, please contact me and I will give you the information needed for you to translate it.
Move the buttons on the YouTube video page.
Download the video in different formats and qualities
Repeat the video
Prevent auto play/buffering.
Choose your prefered quality to be played by default
Auto hide controlbar and/or progressbar.
Scroll to player
Change default volume
Mute as default
Always repeat video
Player shortcuts outside the player
Turn Light On/Off
You can find a more detailed explanation about the features in YouTube Center here: Github Wiki.
You're always welcome to give me suggestion, critic and compliments.