รบกวนขอ code php เปลี่ยนนามสกุลไฟล์ convert เป็นแบบ .mp4 หน่อยครับ !!!

<?
	session_start();
	if($_SESSION['UserID'] == "")
	{
			header('Location: login.php');
		exit();
	}
	include('include/connect.php');
	$strSQL = "SELECT * FROM member WHERE UserID = '".$_SESSION['UserID']."' ";
	$objQuery = mysql_query($strSQL);
	$objResult = mysql_fetch_array($objQuery);

	if(move_uploaded_file($_FILES["filUpload"]["tmp_name"],"video/".$_FILES["filUpload"]["name"]))
	{
		
		echo "<script>alert('Upload file successfully!');</script>";
		echo "<script>window.top.window.showResult('1');</script>";
		function Random($length){
			$possible = "ABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890";
		$str = "";
		while(strlen($str)<$length){
				$str.=substr($possible,(rand()%strlen($possible)),1);
		}
		return $str;
	}
	$random = Random(15);

		include 'include/connect.php';
		$objDB = mysql_select_db("video");
		$strSQL = "INSERT INTO files ";
		$strSQL .="(UserID,v,Name,FilesName,Size,ContentType) 
		VALUES ('".$_SESSION['UserID']."','$random','".$_POST["txtName"]."' ,'".$_FILES["filUpload"]["name"]."' ,'".$_FILES["filUpload"]["size"]."' ,'".$_FILES["filUpload"]["type"]."')";
		$objQuery = mysql_query($strSQL);		

	}
?>