A while back, Google Chrome disabled Youtube Center (a third party app that's not available from the Chrome Web Store) for our protection. Should you want to live your life dangerously, here is one way to reenable it courtesy of the folks at Reddit. Basically, you would need to install a script addon (similar to Greasemonkey) and then install Youtube Center via that. The steps:
1) Go here and install the extension Tampermonkey:
2) Go here and install "YouTubeCenter.user.js" from YePpHa's (i.e., the author of Youtube Center) repository:
And in case you come across this page randomly--Youtube Center is useful (for me) for disabling DASH playback and downloading Youtube videos. DASH playback is the "feature" that stops the video from downloading completely when you pause. This is very annoying if the internet connection is slow and you want to buffer the video completely before viewing.
Update 1 - 20141018: It seems if I use the update URL https://yeppha.github.io/downloads/YouTubeCenter.user.js for the script and enable the auto update option for Tampermonkey, the Youtube Center script will update itself. See picture below:
Alternatively, you can also start a new (empty) script (if you have not already install Youtube Center) and paste in the content of the js file. Then, just save the script.