Чтобы ютуб отображался вот так:

Я делал вот так, soundcloud не работает!:

<?php
define("TAG_VIDEO",      1);
define("TAG_PHOTO",      2);
define("TAG_YOUTUBE",    3);
define("TAG_URL",        4);
define("TAG_SOUNDCLOUD", 5);

function _find_tags($str_message, $int_tag_type)
{
  $arr_files = array();


  if($int_tag_type == TAG_VIDEO)
  {
    if(preg_match_all('/@v:(.*?);/', $str_message, $arr_files))
      return $arr_files;
    else
      return '';
  }
  
  else if($int_tag_type == TAG_PHOTO)
  {
    if(preg_match_all('/@i:(.*?);/', $str_message, $arr_files))
      return $arr_files;
    else
      return '';
  }


  else if($int_tag_type == TAG_YOUTUBE)
  {
    if(preg_match('%(?:youtube(?:-nocookie)?\.com/(?:[^/]+/.+/|(?:v|e(?:mbed)?)/|.*[?&]v=)|youtu\.be/)([^"&?/ ]{11})%i', $str_message, $arr_video))
      return '<iframe width="100%" height="300px" src="https://www.youtube.com/embed/' . $arr_video[1] . '" frameborder="0" allowfullscreen></iframe>';
    else
      return '';
  }


  else if($int_tag_type == TAG_URL)
  {
    if(preg_match("/\b(?:(?:https?|ftp):\/\/|www\.)[-a-z0-9+&@#\/%?=~_|!:,.;]*[-a-z0-9+&@#\/%=~_|]/i", $str_message) 
       && !preg_match('%(?:youtube(?:-nocookie)?\.com/(?:[^/]+/.+/|(?:v|e(?:mbed)?)/|.*[?&]v=)|youtu\.be/)([^"&?/ ]{11})%i', $str_message)) 
      return $str_message;
    else
      return '';
  }
   
  /*Not implemented yet - soundcloud.com*/
  else if($int_tag_type == TAG_SOUNDCLOUD)
  {
    return '';
    if(preg_match("/\bhttps{0,1}:\/\/w{0,3}\.*soundcloud\.com\/([A-Za-z0-9_-]+)\/([A-Za-z0-9_-]+)[^< ]*/i", $str_message, $arr_result)) 
      return '<iframe width="100%" height="450px" scrolling="no" frameborder="no" src="' . $arr_result[0] . '"></iframe>';
    else
      return '';  
  }
}