You can control the SPEED in youtube

One of the most valuable option in youtube of today is the speed control: You can decide if it goes slower than normal or speed the video up.

Here you have the control button:

If this option is not available at your youtube window you maybe are missing the add-on called HTML5 . All things remain the same on your youtube window but you just get the control button!

Place your cursor on the youtube window and RIGHT click. This click brings up a list of options and you take the HTML line.