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Autopause video

Pause videos playing in background tabs when a video starts playing in the foreground tab

// ==UserScript==
// @name         Autopause video
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  Pause videos playing in background tabs when a video starts playing in the foreground tab
// @author       Kirill Skliarov
// @match        *://*/*
// @license      MIT 
// @grant        none
// ==/UserScript==

(function() {
    'use strict';

    const video = document.querySelector('video');
    if (video) {
        const channel = new BroadcastChannel('AutoPauseVideoInBackgroundTabs');
        video.addEventListener('play', () => channel.postMessage(null));
        channel.addEventListener('message', () => video.pause());
    }
})();