static File youtubeDLExtractDestination(S youtubeDLOutput) {
  printIndent("XX ", youtubeDLOutput);
  S s = afterFirstOccurrenceOf(youtubeDLOutput,
    //"[download] Destination: "
    "Destination:"
  );
  if (s != null)
    ret newFile(trim(firstLine(s)));
  int i = indexOf(youtubeDLOutput, " has already been downloaded");
  if (i < 0) null;
  ret newFile(trim(dropPrefix("[download]", lastLine(takeFirst(youtubeDLOutput, i)))));
}