YouTube - Always Theater Mode

Set the default viewing mode to Theater Mode.
目前為 2017-08-31 提交的版本，檢視最新版本。
安裝腳本 ?
換行
// ==UserScript==
// @name        YouTube - Always Theater Mode
// @namespace   r-a-y/youtube/theater
// @description Set the default viewing mode to Theater Mode.
// @include     http://www.youtube.com/watch*
// @include     https://www.youtube.com/watch*
// @version     1.3.4
// @grant       none
// @run-at      document-start
// @license     GPL v3
// ==/UserScript==

// Ensure unsafeWindow object is available both in firefox and chrome
//
// Props Anon via YouTube Cinema Mode userscript
// https://greasyfork.org/en/scripts/10417-youtube-cinema-mode
function installUnsafewindowPolyfill()
{
	if (typeof unsafeWindow === 'undefined')
	{
		if (typeof XPCNativeWrapper === 'function' && typeof XPCNativeWrapper.unwrap === 'function')
			unsafeWindow = XPCNativeWrapper.unwrap(window);
		else if (window.wrappedJSObject)
			unsafeWindow = window.wrappedJSObject;
	}
}

// Disable SPF (Structured Page Fragments), which prevents properly attaching to page load events when navigation occurs
// Will also disable the red loading bar.
//
// Props Anon via YouTube Cinema Mode userscript
// https://greasyfork.org/en/scripts/10417-youtube-cinema-mode
function disableSPF()
{
	if (unsafeWindow._spf_state && unsafeWindow._spf_state.config)
	{
		unsafeWindow._spf_state.config['navigate-limit'] = 0;
		unsafeWindow._spf_state.config['navigate-part-received-callback'] = function (targetUrl) { location.href = targetUrl; }
	}

	setTimeout(disableSPF, 50);
}

// flash + html5 requires manually resizing the stage
function resizeStage() {
	var playlist,
		newPlayer = document.querySelector('button.ytp-size-button');

	// 2017 redesign.
	if ( newPlayer ) {
		newPlayer.click();

	// Older.
	} else {
		document.getElementById('page').className = "watch watch-stage-mode watch-wide";
		document.getElementById('player').className = "content-alignment watch-medium";
		document.getElementById('watch7-container').className = "watch-wide";

		// handle playlists
		playlist = document.getElementById('watch-appbar-playlist');
		if (playlist) {
			playlist.setAttribute('style', 'top:120px');
		}
	}
}

/** TIME FOR SOME ACTION! **/

// get rid of SPF
installUnsafewindowPolyfill();
disableSPF();

// resize after document is loaded
window.addEventListener ("load", function() {
	resizeStage();
});