"YouTube Kid Mode" for Tampermonkey

youtube_kid_mode.js

// ==UserScript==
// @name         YouTube Kid Mode
// @description  Don't show recommendations at the end of YouTube videos
// @version      0.1
// @namespace    http://www.xtagon.com/
// @copyright    2012 Justin Workman
// @match        http://www.youtube.com/watch*
// @match        http://www.youtu.be/*
// @match        http://youtu.be/*
// ==/UserScript==

// See http://www.reddit.com/r/SomebodyMakeThis/comments/16gtte/

function replace_video()
{
	var video_id_regex = /(?:http:\/\/)?(?:www\.)?(?:youtube\.com|youtu\.be)\/(?:watch\?v=)?(.+)/g;
	var embed_code_pattern = '<iframe width="640" height="390" src="http://www.youtube.com/embed/$1?rel=0" frameborder="0" allowfullscreen></iframe>';
	var embed_code = window.location.href.replace(video_id_regex, embed_code_pattern);
	var player_root_element = document.getElementsByClassName("player-root")[0];
    	
	player_root_element.innerHTML = embed_code;
}

// Set a short delay before replacing YouTube's player embed code
// It doesn't work without the delay, but it can probably be tweaked
setTimeout(replace_video, 500);