You can even do fun things like transcode a stream into a format that omxplayer can handle and render a video straight onto a Raspberry Pi without having to download it (and without X11)
'omxplayer' '--blank' '--aspect-mode' 'stretch' <(youtube-dl -o - --audio-format m4a --recode-video mp4 'https://www.youtube.com/watch?v=MKNYsKwM6HI')