Tampermonkey script for fixing the embedded YouTube player (remove play button, hide GUI faster)

// ==UserScript==
// @name         YouTube Embed Cleaner - Instant Hide + Fullscreen Timeout
// @namespace    custom
// @version      1.5
// @match        https://www.youtube.com/embed/*
// @match        https://www.youtube-nocookie.com/embed/*
// @grant        none
// @run-at       document-idle
// ==/UserScript==

(function () {
    'use strict';

    const HIDE_AFTER_MS = 1000;

    const style = document.createElement('style');

    style.textContent = `
        /* Remove dark gradient/background permanently */
        .player-controls-background-container,
        .player-controls-background {
            background: transparent !important;
            background-image: none !important;
            opacity: 0 !important;
            pointer-events: none !important;
        }

        /* Hide main UI */
        html.tm-controls-hidden player-top-controls,
        html.tm-controls-hidden player-middle-controls,
        html.tm-controls-hidden player-bottom-controls,
        html.tm-controls-hidden yt-progress-bar,

        html.tm-controls-hidden .player-controls-top,
        html.tm-controls-hidden .player-controls-middle,
        html.tm-controls-hidden .player-controls-bottom,

        html.tm-controls-hidden .ytmVideoInfoOverlay,

        html.tm-controls-hidden .ytwPlayerTopControlsHost,
        html.tm-controls-hidden .ytwPlayerMiddleControlsHost,
        html.tm-controls-hidden .ytwPlayerBottomControlsHost,

        /* Share / action menu */
        html.tm-controls-hidden player-fullscreen-action-menu,
        html.tm-controls-hidden .ytwPlayerFullscreenActionMenuHost,

        /* More-videos / thumbnail overlays */
        html.tm-controls-hidden .videoThumbnailGroupOverlayBottomLeftRightGroup,
        html.tm-controls-hidden .videoThumbnailGroupOverlayLeftRightGroup,
        html.tm-controls-hidden ytm-thumbnail-overlay-time-status-renderer {

            opacity: 0 !important;
            visibility: hidden !important;
            pointer-events: none !important;
            transition: none !important;
            animation: none !important;
        }

        /* Remove the large center play/pause control */
        player-middle-controls,
        .ytwPlayerMiddleControlsHost,
        .player-controls-middle {
            display: none !important;
        }

        /* Disable YouTube fade delay */
        player-top-controls,
        player-middle-controls,
        player-bottom-controls,
        yt-progress-bar,
        .player-controls-top,
        .player-controls-middle,
        .player-controls-bottom,
        .ytmVideoInfoOverlay,
        player-fullscreen-action-menu {
            transition: none !important;
        }
    `;

    document.head.appendChild(style);

    let hideTimer = null;

    function hideControls() {
        clearTimeout(hideTimer);
        document.documentElement.classList.add('tm-controls-hidden');
    }

    function showControls() {
        document.documentElement.classList.remove('tm-controls-hidden');
    }

    function resetHideTimer() {
        showControls();

        clearTimeout(hideTimer);

        hideTimer = setTimeout(() => {
            hideControls();
        }, HIDE_AFTER_MS);
    }

    /*
     * Any activity inside the player:
     * show UI and restart 2-second countdown.
     */
    window.addEventListener('mousemove', resetHideTimer, { passive: true });
    window.addEventListener('mousedown', resetHideTimer, { passive: true });
    window.addEventListener('keydown', resetHideTimer);

    /*
     * Entering the player also starts the countdown.
     */
    window.addEventListener('mouseover', resetHideTimer, { passive: true });

    /*
     * Leaving the iframe still hides instantly.
     */
    window.addEventListener('mouseout', (event) => {
        if (
            event.relatedTarget === null &&
            event.toElement === null
        ) {
            hideControls();
        }
    });

    document.documentElement.addEventListener('mouseleave', hideControls);

    /*
     * Start hidden.
     */
    hideControls();
})();