Open up a YouTube video and after it starts take your cursor and click anywhere along the timeline (that’s the red bar found along the bottom of the screen indicating video duration)
After you click on the video, let it buffer for a second or two then click any number on your keyboard from 1-9. The video will jump from segment to segment respective to the numbers clicked. If you multi-click a number in succession you can scratch…kind of. The number 0 will take you back to the start of the video.
Give it a try on this video: