private function setVideoPlaylist($id, $playlist)
 {
     $updateVideo = new updateVideo();
     if ($playlist >= 0) {
         $updateVideo->addVideoToPlaylist($id, $playlist);
     }
 }
<?php

/* PASSWORD PROTECT */
require_once dirname(__FILE__) . '/../inc/class.passwordProtect.php';
/* PASSWORD PROTECT */
if (isset($_GET['id'])) {
    require_once dirname(__FILE__) . '/../inc/class.updateVideo.php';
    $updateVideo = new updateVideo();
    $updateVideo->addVideoToPlaylist($_GET['id'], $_GET['playlist']);
    exit;
}
?>
<!DOCTYPE html>
<html>
<head>
<script src="//cdnjs.cloudflare.com/ajax/libs/jquery/1.10.2/jquery.min.js"></script>
<script src="./js/main.js"></script>
</head>
<body>
	<form id="video-form">
		ID: <input id="input-id" type="text" name="id" value=""> <span id="video-title"></span><br>
		Playlist: 
		<select id="input-playlist">
			
		</select>
		<br>
		<div id="submit-button">Submit</div>
	</form>
</body>
</html>