Bookmarklet to get Reddit Video fallback URL (tested in Firefox)

reddit_video_fallbackURL_bookmarklet.js

javascript:(function() {
  var currentUrl = window.location.href;
  if (!currentUrl.includes("reddit")) {
    alert("This bookmarklet is designed for Reddit pages only.");
    return;
  }
  var jsonUrl = currentUrl + ".json";
  fetch(jsonUrl)
    .then(response => response.json())
    .then(data => {
      var mediaData = data[0]?.data?.children[0]?.data?.media;
      var fallbackUrl = mediaData?.reddit_video?.fallback_url;
      if (fallbackUrl) {
        alert("Fallback URL: " + fallbackUrl);
      } else {
        alert("No 'fallback_url' property found in the JSON data.");
      }
    })
    .catch(error => {
      alert("Error fetching the JSON data: " + error);
    });
})();