YouTube user reveals YouTube’s secret keyboard shortcuts through a viral video
If you were under the impression that pressing the spacebar on YouTube pauses the video, you are mistaken. In fact pressing the  spacebar while watching a YouTube video, makes the screen jump to the comments section.
So which key can pause the video in YouTube?
YouTube user, GradeAUnderA did some plain old style detective work and found out that pressing K while watching the YouTube video pauses it. He also found that pressing J will take the YouTube video back 10 seconds and similarly pressing L will take it 10 seconds forwards.
GradeAUnderA made a YouTube video to showcase his findings and the video has gone viral with around 600K + views. In fact, it featured on the front page of Reddit through Sunday.
You can also skip to parts in the video using the number keys above the letter keys.
I don’t know if it’s out of nine parts (cause 1 – 9) or how else it works, but I’m guessing it’s like that.
1 would be 1/9th into the vi, 5 would be 5/9th s into it.. etc..
Forgot to mention that you can also use the space bar to redo an action.
Specifically the last action you did when you clicked.
So if you click on the full screen button, then press the space bar, it will un (or re) full screen.
You can also use the arrow keys on your keyboard to change the volume, (up/down) and scrub through the video (left/right).