$apiKey = "AIzaSyDfxFwpn_hUMWnvwA22D5FldT8f6wPgw5Y";  //Api key
$videoid = "aNQsM1trwPk"; //Youtube Video ID'si
$dataUrl = "https://www.googleapis.com/youtube/v3/videos?id=".$videoid."&part=contentDetails&key=".$apiKey;
 
$Baglan = file_get_contents($dataUrl);
$jData = json_decode($Baglan);
$sure  = $jData->items[0]->contentDetails->duration;
 
function sure_cevir($sure){
   $saat = strpos($sure,"H");
   $dk = strpos($sure,"M");
   if($saat > 0){ //Saat varsa
   preg_match('#PT(.*?)H(.*?)M(.*?)S#',$sure,$tamsaat);
   $tamsaat = $tamsaat[1].":0".$tamsaat[2].":".$tamsaat[3];
   }else if($dk > 0 && $saat == 0){ //Dk varsa
      preg_match('#PT(.*?)M(.*?)S#',$sure,$tamsaat);
      $tamsaat = $tamsaat[1].":".$tamsaat[2];
   }else{
      preg_match('#PT(.*?)S#',$sure,$tamsaat);
      $tamsaat = "0:".$tamsaat[1];
   }
   return $tamsaat;
}
echo sure_cevir($sure);
// print_r($tamsure);