A visual cheat-sheet for the 18 keyboard shortcuts found on YouTube.com.
Space — Play/Pause when the seek bar is selected, activate a button if a button has focus
K — Play/Pause in player
Left/Right — Seek backward/forward 5 seconds
J — Seek backward 10 seconds in player
L — Seek forward 10 seconds in player
Home — Seek to the beginning of the video
End — Seek to the last seconds of the video
Up — Increase volume 5%
Down — Decrease volume 5%
1-9 — Seek to the 10-90% of the video
0 — Seek to the beginning of the video
Shift 1 — Move between H1 headers
/ — Go to search box
F — Activate full screen, press again (or Esc) to exit
C — Activate closed captions and subtitles, press again to hide
Shift N — Move to the next video
Shift P — Move to the previous video
I — Launch the Miniplayer
. — Move forward a single frame (while paused)
, — Move back a single frame (while paused)