Fast forward and rewind hotkeys userscript for VK and Boosty. Key D: fast forward 1 second. Key A: rewind 1 second. Alt+C: copy current timecode.

video_hotkeys.user.js

// ==UserScript==
// @name         Video hotkeys for VK, Rutube, Boosty - fast forward and rewind
// @namespace    pongo
// @version      2024-10-30
// @description  Adds hotkeys for fast forwarding (key D) and rewinding (key A) videos by 1 second on VK and Boosty. Press alt+c for copy current timecode.
// @author       pongo
// @match        https://vk.com/video-*
// @match        https://boosty.to/*/posts/*
// @match        https://rutube.ru/video/*
// @grant        GM_setClipboard
// ==/UserScript==

(function() {
    'use strict';

    const { isVideoTarget, getVideo } = initSite();

    window.addEventListener('keydown', function(e) {
        //console.log(e);
        switch (e.code) {
            case "KeyD":
                if (!isVideoTarget(e)) return;
                e.preventDefault();
                seek(1, getVideo(e));
                return;
            case "KeyA":
                if (!isVideoTarget(e)) return;
                e.preventDefault();
                seek(-1, getVideo(e));
                return;
            case "KeyC":
                if (!isVideoTarget(e)) return;
                if (!e.altKey) return;
                e.preventDefault();
                copyCurrentTime(getVideo(e));
                return;
        }
    });

    function seek(seconds, video) {
        const time = getTime(video);
        video.currentTime = time + seconds;
    }

    function copyCurrentTime(video) {
        const time = getTime(video);
        const timecode = new Date(time * 1000).toISOString().slice(11, 19); // https://stackoverflow.com/a/25279340/136559
        GM_setClipboard(timecode, "text");
    }

    function getTime(video) {
        return parseInt(video.currentTime, 10);
    }

    function initSite() {
        switch (location.hostname) {
            case 'vk.com':
                return {
                    isVideoTarget(e) {
                        return e.target.classList.contains('videoplayer');
                    },
                    getVideo() {
                        return document.querySelector('#video_player video');
                    }
                };
            case 'boosty.to':
                return {
                    isVideoTarget(e) {
                        return e.target.className === 'shadow-root-container';
                    },
                    getVideo(e = undefined) {
                        const target = e?.target ?? document.querySelector('vk-video-player .shadow-root-container');
                        return target.shadowRoot.querySelector('video');
                    }
                };
            case 'rutube.ru':
                return {
                    isVideoTarget(e) {
                        return e.target.className.includes('player') || e.target.querySelector('video') != null;
                    },
                    getVideo() {
                        return document.querySelector('.video-player video');
                    }
                };
            default:
                alert(`[hotkey-video] hostname "${location.hostname}" not found`);
        }
    }
})();