You will soon be able to easily copy and save a video frame on Android،
Taking the perfect screenshot of a video hasn't always been the easiest task on desktop or mobile. While you could still use the usual screenshot tools on either platform, it wasn't always possible to get a clean output without the player menus and controls being visible , unless you crop a significant portion of the image. Fortunately, this problem has now been somewhat resolved on desktop, and an Android solution appears to be on the way as well.
“Save video image as…” option in Google Chrome Desktop
However, recent code updates indicate that Google will soon allow you to record video footage directly from YouTube on Android devices. This was also spotted by the same user via another commit on the Chromium Gerrit repository called “Mark video frame copy/save features as disabled on Android”, with a description clearly stating “These features are not yet implemented on Android. To be prepared for implementation, mark them as disabled until they are ready to launch.”
This indicates that plans are underway to bring this handy tool to Android, although there is no clear indication of how it will be implemented. Since YouTube has its own dedicated app on Android, I assume it will be part of the interface and added as an option in a video's settings, where you would normally choose the video's playback speed and quality . This is just a guess, as no screenshots are available yet.