Use the keyboard to control online video/audio playback speed, perfect support for Youtube. It control video speed up, slow down, advance and rewind with shortcuts. Faster HTML5 Video HTML5 video provides a native API to accelerate playback of any video. The problem is many players either hide or limit this functionality. For the best results, playback speed adjustments should be easy and frequent to match the pace and content being covered: we don't read at a fixed speed, and similarly, we need an easy way to accelerate the video, slow it down, and quickly rewind the last point to listen to it a few more times. Once the extension is installed simply navigate to any page that offers HTML5 video (example), and you'll see a speed indicator in top left corner. Hover over the indicator to reveal the controls to accelerate, slowdown, and quickly rewind or advance the video. Or, even better, simply use your keyboard:

S - decrease playback speed.
D - increase playback speed.
R - reset playback speed.
Z - rewind video by 10 seconds.
X - advance video by 10 seconds.
V - show/hide controller.

You can customize and reassign the default shortcut keys in the extensions settings page as well as add additional shortcut keys to match your preferences. As an example, you can assign multiple "preferred speed" shortcuts with different values, allowing you to quickly toggle between your most frequently used speeds. To add a new shortcut, open extension settings and click "Add New". Unfortunately, some sites may assign other functionality to one of the shortcut keys - this is inevitable. As a workaround, the extension listens both for lower and upper case values (i.e. you can use Shift-<shortcut>) if there is other functionality assigned to the lowercase key. This is not a perfect solution since some sites may listen to both, but it works most of the time.