Open the YouTube video you want to watch and press Ctrl+M. This keyboard shortcut can make YouTube hide the process bar even you haven’t paused the YouTube video.
To capture a Youtube video screenshot without the player controls, use the Hyde browser extension and the keystroke Ctrl+M to hide/unhide the controls.
Further, one can use the Windows Snipping Tool via Win-Shift-S to effect a screenshot to the clipboard for saving and editing.
https://youtubedownload.minitool.com/youtube/how-to-hide-youtube-bar.html