Chunk, Snippet & Php function...

if(!function_exists(FUNCTION_NAME)){
  function FUNCTION_NAME(){
    stuff here...
  }
}

<?php

if(!function_exists(FUNCTION_NAME)){
    function FUNCTION_NAME(){
        stuff here....
    }
}

$output ='';
$output .=$modx->runSnippet("Ditto",array(
                "tpl"  => "CHUNK_NAME",
                "param2"  => "value2",
                "param3"  => "param3"
                ));
                // note no comma after the last param

return $output;
?>

function $embedVideo($video,$giro,$size) {
  if (strpos($video, "#") !== FALSE) {
      $cut = explode("#", $video);
	  $video = $cut[0];
  }	
  if( $size == "small") { 
      $img_set = "&w=130&h=70&zc=1&fltr[]=wmi|[(base_url)]/assets/templates/luigicinque/img/play_wm.png|68x38|66|50|50|0";
      $giro = 0;
  }
  else {
    $img_set = "&w=270&h=150&zc=1&fltr[]=wmi|[(base_url)]/assets/templates/luigicinque/img/play_wm.png|135x75|66|85|85|0";
  }  
  $rel = "rel=\"shadowbox;width=640;height=385\"";
  if (is_int($giro/2) == true){
	$class = "mrg";
  }
  else { $class = ""; }
  $video = trim($video);

  if (strpos($video, "youtube") !== FALSE) {
    $split = explode("&",$video);
    $split2 = explode("=",$split[0]);
    $v_id = $split2[1];
    $img = "[(base_url)]image.php?src=http://img.youtube.com/vi/".$v_id."/0.jpg";
    echo '<a href="http://www.youtube.com/embed/'.$v_id.'?rel=0&autoplay=1" '.$rel.'><img src="'.$img.$img_set.'" class="gray '.$class.'"></a>'."\n";
  }
  if (strpos($video, "vimeo") !== FALSE) { 
    $split = explode("vimeo.com/",$video); 
    $v_id = $split[1];
    $json = @json_decode(file_get_contents('http://vimeo.com/api/oembed.json?url=http://vimeo.com/'.$v_id));
    $thumb = $json->thumbnail_url;
    $img = "[(base_url)]image.php?src=".$thumb;
    echo '<a href="http://player.vimeo.com/video/'.$v_id.'?title=0&byline=0&portrait=0&autoplay=1" '.$rel.'><img src="'.$img.$img_set.'" class="gray '.$class.'"></a>'."\n";
  }
  if (strpos($video, "dailymotion") !== FALSE) {
    $split = explode("video/",$video);
    $v_id = $split[1];
    $split = explode("_",$v_id);
    $v_id = $split[0];
    $img = "[(base_url)]image.php?src=http://www.dailymotion.com/thumbnail/video/".$v_id;
    echo '<a href="http://www.dailymotion.com/embed/video/'.$v_id.'?autoPlay=1" '.$rel.'><img src="'.$img.$img_set.'" class="gray '.$class.'"></a>'."\n";
  }
}