youtube.user.js

// ==UserScript==
// @name       /b/ideo loco
// @namespace  tranquilo papá
// @version    0.1
// @include    http*://www.nido.org/b/*
// @exclude
// ==/UserScript==

var main=function(){$(".post .body").each(function(){var a=$(this).html().match(/.*?(youtube.com\/.+?v=([^"]*)")/);a&&11==a[2].length&&(id=a[2],$(this).prepend('<iframe width="560" height="315" src="https://www.youtube.com/embed/'+id+'" frameborder="0" allowfullscreen></iframe><br>'))})};script=document.createElement("script");script.type="text/javascript";script.textContent="("+main.toString()+")();";document.body.appendChild(script);