static S embedYoutube_newer_autoplay(S youtubeID) {
  ret embedYoutube_newer_autoplay(youtubeID, 400); // no volume level at 300
}

static S embedYoutube_newer_autoplay(S youtubeID, int w) {
  int h = sixteenToNine(w);
  youtubeID = extractYouTubeID(youtubeID);
  ret ([[<iframe width="]] + w + [[" height="]] + h + [[" src="https://www.youtube.com/embed/{*}?autoplay=1" frameborder="0" allow="autoplay; encrypted-media" allowfullscreen></iframe>]]).replace("{*}", youtubeID);
}