= youtube-dl =
 * https://github.com/ytdl-org/youtube-dl
 * curl -L https://yt-dl.org/downloads/latest/youtube-dl -o ~/scripts/youtube-dl
 * chmod 755 ~/scripts/youtube-dl
 * youtube-dl -F https://www.youtube.com/watch?v=aaaa
 * youtube-dl -f 249 https://www.youtube.com/watch?v=aaaa