Twitch Auto Fullscreen (tampermonkey)

twitch-auto-fullscreen.user.js

// ==UserScript==
// @name         Twitch Auto Fullscreen
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  Enter fullscreen after a countdown (ESC to cancel)
// @author       You
// @include      https://www.twitch.tv/*
// @include      https://twitch.tv/*
// @require https://cdnjs.cloudflare.com/ajax/libs/umbrella/3.1.0/umbrella.min.js
// @grant        GM_addStyle
// @run-at       document-idle
// ==/UserScript==

GM_addStyle(".fscounter { text-align: center; position: absolute; top: calc(50% - 5rem); width: 100%;}");
GM_addStyle(".fscounter span { font-size: 10rem; position: relative; padding: 0; margin: 0; line-height: 1em; }");
GM_addStyle(".fscounter span { text-shadow: 1px 1px 2px black, 0 0 25px white, 0 0 5px yellow; }");

(function() {
    'use strict';

    const html_fscounter = '<div class="fscounter"><span></span></div>'
    let pathname = ''

    new MutationObserver(() => {
        const userRegExp = /^\/[a-zA-Z0-9\-_]+$/
        const userUrlTrigger = location.pathname.match(userRegExp)
        const isSearch = location.pathname.match(/^\/search/)

        if (pathname !== location.pathname && userUrlTrigger && !isSearch) {
            const fsbutton = u('.player-button.qa-fullscreen-button')

            if (fsbutton.length) {
                if (!u('.video-player.video-player--fullscreen').length) {
                    startFullscreenCounter(3, fsbutton)
                }

                pathname = location.pathname
            }
        }
    }).observe(document.getElementsByTagName('title')[0] || document, { childList: true, subtree: true });

    function startFullscreenCounter(countdown, btn) {
        const videoEl = u('.video-player video')
        const videoContainer = u(videoEl).parent()

        if (videoContainer) {
            let fscounter = u(videoContainer).append(() => html_fscounter)
            const fsc_span = u(fscounter).find('span')

            let counter = null

            u(document).handle('keyup', (e) => {
                if(counter && e.key === "Escape") {
                    clearInterval(counter)
                }
            })

            counter = setInterval(() => {
                u(fsc_span).html(countdown--)

                if (u('.video-player.video-player--fullscreen').length) clear()
                else if (countdown === -1) {
                    u(btn).trigger('click')
                    clear()
                }
            }, 1000)

            if (counter) {
                u(document).handle('keyup', escHandler)
                u('.video-player').on('click', clear)
            }

            function escHandler(e) {
                if (counter && e.key === "Escape") clear()
            }

            function clear() {
                u(document).off('keyup', escHandler)
                u('.video-player').off('click', clear)
                if (counter) clearInterval(counter)
                u(fscounter).find('.fscounter').remove()
            }
        }
    }

})();

Does this still work? Nothing happens when I enter a stream.