Old version, still works but has some glitches

search_hobune_for_all.js

// ==UserScript==
// @name        Search Hobune for all videos on page
// @namespace   hobune.stream
// @match       https://www.youtube.com/*
// @grant       GM_xmlhttpRequest
// @connect     hobune.stream
// @version     1.0
// @author      Rebane
// @description 1/8/2021, 12:02:22 PM
// ==/UserScript==

let hobuneEndpoint = "https://hobune.stream/tpa-h/videos/";

function checkVideo(vidID){
    GM_xmlhttpRequest ( {
        method:     'GET',
        url:        hobuneEndpoint + vidID,
        onload:     function (vidID) {
                        return (response) => {
                          let obj = document.getElementsByClassName("timecode-" + vidID)[0];
                          obj.innerText = (response.status == 200 ? "✔️ " : "❌ " ) + obj.innerText;
                        }
                    }(vidID)
    } );
}

function checkAllVideos(){
  setTimeout(() => {
    document.querySelectorAll("span.ytd-thumbnail-overlay-time-status-renderer").forEach(obj => {
      let vidID = obj.parentElement.parentElement.parentElement.href.split("=")[1];
      vidID = vidID.replace("&t", "").replace(/[^a-zA-Z0-9_-]/g, "");
      obj.classList.add("timecode-" + vidID);
      checkVideo(vidID);
    });
  }, 5000);
}

checkAllVideos();