check youtube iframe code

I have a piece of code that checks the youtube embed code in this format: My PHP code looks like this now:

            //Check Embed Code
            $embedCode = $postData['embedCode'];  



            /*if(isset($matches[1]))
            {*/
                preg_match('/<param (.*)">/i', $embedCode, $matches);
                if(isset($matches[1]))
                {
                    if(str_replace('movie','as',$matches[1]))
                    {
                        $val=explode('>', $matches[1]);
                        $str=str_replace('name','',$val[0]);
                        $str=str_replace('=','',$str);
                        $str=str_replace('"','',$str);
                        $str=str_replace('value','',$str);
                        $str=str_replace('movie','',$str);
                        $str=str_replace('http://www.youtube.com/v/','',$str);
                        $str=trim($str);
                        $all=$this->GetYouTubeVideoURL($str);   
                        // GET MEDIA URL
                        $all_infos=$this->GrabYouTube("http://www.youtube.com/watch?v=$str"); //GET THUMBNAIL URL
                        $postData['youtube_video_id'] = $all_infos['youtube_video_id'];
                        $postData['image_url']         = $all_infos['thumbnail_url'];

                    } else {

                        $mainframe->enqueueMessage(JText::_('EMBED CODE ERROR'), 'error');
                        $isValid = false;
                    }
                } else {

                    $mainframe->enqueueMessage(JText::_('EMBED CODE ERROR'), 'error');
                    $isValid = false;
                }
            /*} else {

                    $mainframe->enqueueMessage(JText::_('EMBED CODE ERROR'), 'error');
                    $isValid = false;
            }*/



        }