The best suggestion for you would be to use SMplayer and create a new playlist in it with the video links you want to watch later and never fear of messing thin

The best suggestion for you would be to use SMplayer and create a new playlist in it with the video links you want to watch later and never fear of messing things up. It uses either youtube-dl or yt-dlp behind the scenes for playing the videos while downloading them on the fly, so it works flawlessly in cases like yours.