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Fullscreen Video Speed Controller

Control playback speed, and seek for fullscreen videos

  1. // ==UserScript==
  2. // @name         Fullscreen Video Speed Controller
  3. // @version      2.1.1
  4. // @description  Control playback speed, and seek for fullscreen videos
  5. // @author       Wanten
  6. // @copyright    2025 Wanten
  7. // @license      MIT
  8. // @supportURL   https://gist.github.com/WantenMN/c0afabc32a911d4dd10e06cff6bcb211
  9. // @homepageURL  https://gist.github.com/WantenMN/c0afabc32a911d4dd10e06cff6bcb211
  10. // @namespace    https://greasyfork.org/en/scripts/536243
  11. // @run-at       document-end
  12. // @match        https://*/*
  13. // @grant        none
  14. // ==/UserScript==
  15.  
  16. (function() {
  17.     'use strict';
  18.  
  19.     // Helper function to get the fullscreen video element
  20.     function getFullscreenVideo() {
  21.         if (document.fullscreenElement && document.fullscreenElement.tagName === 'VIDEO') {
  22.             return document.fullscreenElement;
  23.         }
  24.  
  25.         const videos = document.getElementsByTagName('video');
  26.         for (const video of videos) {
  27.             if (video.offsetWidth === window.innerWidth && video.offsetHeight === window.innerHeight) {
  28.                 return video;
  29.             }
  30.         }
  31.         return null;
  32.     }
  33.  
  34.     // Function to set the video speed
  35.     function setVideoSpeed(speed) {
  36.         const video = getFullscreenVideo();
  37.         if (video && video.playbackRate != speed) {
  38.             video.playbackRate = speed;
  39.  
  40.             if (video.playbackRate === 1){
  41.                 // Fix audio/video synchronization issues
  42.                 video.currentTime = video.currentTime;
  43.             }
  44.         }
  45.     }
  46.  
  47.     // Function to seek the video forward or backward
  48.     function seekVideo(offset) {
  49.         const video = getFullscreenVideo();
  50.         if (video) {
  51.             video.currentTime += offset;
  52.         }
  53.     }
  54.  
  55.     // Event listeners for key presses
  56.     document.addEventListener('keydown', function(event) {
  57.         switch(event.key) {
  58.             case 'j':
  59.                 setVideoSpeed(1);
  60.                 break;
  61.             case 'k':
  62.                 setVideoSpeed(2);
  63.                 break;
  64.             case 'l':
  65.                 setVideoSpeed(3);
  66.                 break;
  67.             case 'h':
  68.                 seekVideo(-5); // Rewind 5 seconds
  69.                 break;
  70.             case ';':
  71.                 seekVideo(5); // Fast-forward 5 seconds
  72.                 break;
  73.         }
  74.     });
  75. })();
  76.