Force Flash video on YouTube in Firefox

Published by Xianqiao Wang on October 22nd, 2014

http://www.youtube.com/watch?v=y5JicO2bKec [HTML5]
http://www.youtube.com/v/y5JicO2bKec [Flash] http://www.ghacks.net/2014/10/20/force-flash-video-on-youtube-in-firefox/