Allow rewinding in YouTube livestreams that have it disabled

youtube-livedvr.js

// ==UserScript==
// @name         Force enable YouTube Live Dvr
// @namespace    http://tampermonkey.net/
// @version      2024-01-08
// @description  Allow rewinding in YouTube livestreams that have it disabled
// @author       mat
// @match        https://www.youtube.com/*
// @icon         https://www.google.com/s2/favicons?sz=64&domain=youtube.com
// @grant        GM_webRequest
// @run-at       document-start
// @downloadURL  https://gist.githubusercontent.com/mat-1/cbe94281f8de116b1107c4b0c9c59dae/raw/youtube-livedvr.js
// @updateURL    https://gist.githubusercontent.com/mat-1/cbe94281f8de116b1107c4b0c9c59dae/raw/youtube-livedvr.js
// ==/UserScript==

unsafeWindow.XMLHttpRequest.prototype.open = new Proxy(self.XMLHttpRequest.prototype.open, {
    apply: async (target, thisArg, args) => {
        thisArg.addEventListener('readystatechange', function() {
            if (thisArg.readyState !== 4) return
            if (thisArg.responseURL !== 'https://www.youtube.com/youtubei/v1/player?prettyPrint=false') return
            const parsed = JSON.parse(thisArg.responseText)
            if (!parsed.videoDetails.isLiveDvrEnabled) {
                console.log('livedvr is disabled!')
                parsed.videoDetails.isLiveDvrEnabled = true
            }
            const patchedResponse = JSON.stringify(parsed)
            Object.defineProperty(thisArg, 'response', { value: patchedResponse });
            Object.defineProperty(thisArg, 'responseText', { value: patchedResponse });
        });
        return Reflect.apply(target, thisArg, args);
    }
});