Youtube URL to Embed Code

Working on a new site and wanted to add a function to add embed code from YouTube. I am limiting the amount of html that is allowed to be posted by the users. I also wanted to make sure the user could only embed a video from YouTube. The function I’m working on takes the URL of the YouTube page and parses the source for the embed code. Below is an example on how I am getting the data. The actual function does a lot more filtering of the URL string.

<form action="#" method="get">
<input type="text" name="url" value="YOUTUBE URL">
<input type="submit" name="submit" value="Get Embed Code">


if ($_GET['url'] != "") {
$url file_get_contents($_GET['url']);
$url preg_match('/(input id="embed).*(\/>)/'$url$arr);
$url preg_match('/(&lt;).*(\/object&gt;)/',$arr[0], $result);

 $result html_entity_decode($result[0]);

 echo '<b>The Video...</b><br />';
$result '<br /><br />';
'<b>The embed code...</b><br />';
htmlentities($result) . '<br /><br />';

<br />
<b>How to get the embed code from the linux Command line.</b>
<br />curl '' | egrep '((input id="embed).*/>)' | egrep -o '(&lt;).*(/object&gt;)'