Userscripts.org

There are 4 previous versions of this script.

// ==UserScript==
// @name           YouTube Eliminate Video Ads
// @namespace      http://userscripts.org/users/23652
// @description    Removes video advertisements
// @include        http://*.youtube.com/watch?*
// @include        http://youtube.com/watch?*
// @copyright      JoeSimmons
// @version        1.0.2
// @license        Creative Commons Attribution-Noncommercial 3.0 United States License
// ==/UserScript==

(function(){
var mp = window.document.getElementById('movie_player'),
	mpC = mp.cloneNode(true);
mpC.setAttribute('flashvars', mpC.getAttribute('flashvars').replace(/[\&\?]?(ad_|infringe|invideo|watermark)([^=]*)?=[^\&]*/gi,'').replace(/(^[\&\?]*)|([\&\?]*$)/g,'')+'&invideo=false');
mp.parentNode.replaceChild(mpC, mp);
})();