tampremoney.js

// ==UserScript==
// @name         YoutubeEmbedder
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  try to take over the world!
// @author       Accalia <accalia@elementia.me>
// @match        https://www.youtube.com/watch*
// @match        http://www.youtube.com/watch*
// @grant        none
// ==/UserScript==

(function() {
    'use strict';
    var protocol = location.protocol;
    var videoIdSearch  = /v=([^&]+)(&|$)/.exec(location.search);
    var videoId  = (videoIdSearch || [])[1];
    if (!videoId) {
        return;
    }
    var destination = `${protocol}//www.youtube.com/embed/${videoId}`;
    location.replace(destination);
})();