On
These shortcuts will only work when the video player is in focus. To move the focus try pressing the space-bar to pause and then play the video.

Keyboard Shortcuts for YouTube
Action Shortcut
Toggle play/pause the video Spacebar
Increase volume 5% Up arrow
Decrease volume 5% Down arrow
Go back 5 seconds Left arrow
Go forward 5 seconds Right arrow
Go to Full Screen mode f
Exit Full Screen mode Escape
Child window i
Go to beginning of video Home
Go to end of video End
Mute/unmute video m
Turn captions on/off c
Cycle through options for caption background color b
Move forward 1 frame when video is paused . (period)
Move backward 1 frame when video is paused , (comma)
Increase speed Shift + > (may not work in all browsers) or Shift + . (period)
Decrease speed Shift + < (may not work in all browsers) or Shift + , (comma)
Move to the previous video in a playlist Shift + p
Move to the next video in a playlist Shift + n