use media key to play/pause HTML5 video

media-keyboard.user.js

// ==UserScript==
// @name         Media Keyboard
// @version      0.1
// @description  try to take over the world!
// @author       Francesco Cannizzaro
// @match        *://*/*
// ==/UserScript==

(function() {
    'use strict';
    document.addEventListener('keydown', function(event) {
        var video = document.querySelectorAll('video');
        if (![178, 179].includes(event.keyCode)) return;
        video.forEach(video => {
            if (video.currentTime > 0 && !video.ended) {
                switch (event.keyCode) {
                    case 179:
                        if (video.paused) video.play();
                        else video.pause();
                        break;
                    case 178:
                        video.pause();
                        video.currentTime = 0;
                }
            }
        });
    });
})();