Using video player controls in YouTube is quite straightforward. When you open a video, you'll see the video player with several controls. At the bottom left of the video screen, you'll see the play/pause button, and next to it is the timeline bar which shows the video's progress. You can click anywhere on this bar to skip to a different part of the video. On the right side of the timeline bar, you'll see the video's total length.

Next to the timeline, there are additional controls such as the volume control, the captions/subtitles button (if available), the settings button (where you can adjust playback speed, quality, etc.), the miniplayer button, the theater mode button, and the full-screen button. Hovering over these buttons will show what they do. Remember, you can also use keyboard shortcuts for some controls like spacebar for play/pause, left/right arrow keys to rewind/fast-forward, up/down arrow keys to increase/decrease volume, etc.