browser.webRequest.onBeforeRequest.addListener(
  function(details) {
    const url = new URL(details.url);
    if (url.hostname === "www.youtube.com" || url.hostname === "youtube.com") {
      // Extract the video ID from the URL params
      const videoId = url.searchParams.get("v");
      if (videoId) {
        // Rewrite to the embedded URL format, picking timecode if available
        const timecode = url.searchParams.get("t");
        return {
          redirectUrl: `https://www.youtube-nocookie.com/embed/${videoId}?rel=0` + (timecode ? "&start=" + timecode : "");
        };
      }
    }
  },
  { urls: [
      "*://www.youtube.com/*",
      "*://youtube.com/*"
    ]},
  ["blocking"]
);