// returns youtube-dl output
static S youtubeDownloadVideo(S url) {
  ret youtubeDownloadVideo(url, null);
}

static S youtubeDownloadVideo(S url, File outputDir) {
  Class c = hotwireDependent(#1006739);
  set(c, youTubeOptions := ""); // default video format
  set(c, +outputDir);
  callMain(c, url);
  ret str(get(c, "output"));
}