Disable Youtube Autoplay

no_yt_autoplay.user.js

// ==UserScript==
// @name        Disable YT Autoplay
// @namespace   user@violet.local
//
// @description No more autoplay, that's it
//
// @date        2015-03-15
// @version     1
// @grant       none
// @updateURL   https://gist.github.com/VioletRed/d3678cdc700cd4d62fec/raw/no_yt_autoplay.user.js
// @include *.youtube.com/*
// @include *.youtu.be/*
// ==/UserScript==
//
// Disable yt autoplay

// Injects code into the global scope.
function inject(fn) {
	var script = unsafeWindow.document.createElement('script');
	script.innerHTML = '(' + fn.toString() + ')();';
	unsafeWindow.document.body.appendChild(script);
}
// This function stops the video if we're not looking. Inject
// it into the page. Note that we can't access any variables outside the
// function here.
function kodi_pauseyt() {
	// Returns the player API interface or false if it's not ready.
	function kodi_getPlayer() {
		if (window.document 
				&& window.document.getElementsByTagName
				&& window.document.getElementsByTagName('video')
				&& window.document.getElementsByTagName('video')[0]) {
			player = window.document.getElementsByTagName('video')[0]
			if (!player["pause"])
				return false;
		} else {
			if (window.yt && window.yt.player
					&& window.yt.player.getPlayerByElement
					&& window.yt.player.getPlayerByElement('player-api')
					&& window.yt.player.getPlayerByElement('player-api')["pauseVideo"]) {
				player = window.yt.player.getPlayerByElement('player-api')
			} else {
				return false;
			}
		}
		return player;
	}
	// Listen for the end of the video.
	function kodi_activate() {
                // console.log("GOOOO");
		player = kodi_getPlayer();
		var last_paused = document.documentURI;
		var target = window.document.getElementById("body");
		// create an observer instance
		var observer = new MutationObserver(function(mutations) {
			mutations.forEach(function(mutation) {
				// console.log("How many "+mutation.addedNodes.length);
				// console.log(mutation.type)
				// console.log(mutation.addedNodes) //
				if (mutation.type == "childList" && document.documentURI != last_paused
						&& mutation.addedNodes.length > 0) {
					if (mutation.addedNodes[0].tagName == "IFRAME") {
						kodi_wait(0);
						observer.disconnect();
					}
					}
			});
		});

		// configuration of the observer:
		var config = {
			childList : true,
			characterData : true
		};

		// pass in the target node, as well as the observer options
		observer.observe(target, config);

		// console.log("Active")
		if (player['pause']) { // HTML5
			// console.log("HTML5")
			setTimeout(function(){player.pause()}, 300);
		} else { // Flash
			// console.log("STUPID FLASH");
			setTimeout(function(){player.pauseVideo()}, 1200);
		}
		// if (document.hidden || document.mozHidden || document.webkitHidden)
		// window.yt.player.getPlayerByElement('player-api').pauseVideo();
	}
	// Wait until the YouTube API's ready.
	function kodi_wait(count) {
                // console.log("WAIT");
		if (count < 50) {
			setTimeout(kodi_getPlayer() ? kodi_activate : function() {kodi_wait(count+1)}, 100);
		}
	}
	kodi_wait(0);
};

inject(kodi_pauseyt);

Can you make scripts that set a timer to automatically pause/stop on all Youtube embed videos? Like pause a video after X seconds!!?