Userscripts.org

// ==UserScript==
// @name           Demonoid Auto Check "I understand and agree to the rules"
// @namespace      http://userscripts.org/users/23652
// @description    Auto checks the checkbox that says you agree to the rules
// @include        http://www.demonoid.com/torrent_upload.php5
// @copyright      JoeSimmons
// ==/UserScript==

box = document.getElementById('agree');

if(box && typeof box!='undefined' && box!=null) box.checked = true;