How to Get Frame Accurate Seeking from Video HTML Element?

With example here: https://adhesive-smooth-produce.glitch.me

We're able to see the following works in getting accurate frame count across the entirety of the example video - something not able to be done w/ the currentTime parameter.

  const updateCanvas = (now, metadata) => {
    if (startTime === 0.0) {
      startTime = now;
    }
    
    ctx.drawImage(video, 0, 0, width, height);
    
    let frameOffset = 2
    const frames = Math.round(metadata.mediaTime  * fps) - frameOffset
    fpsInfo.innerText = !isFinite(frames) ? 0 : frames;
    metadataInfo.innerText = JSON.stringify(metadata, null, 2);

    video.requestVideoFrameCallback(updateCanvas);
  };  

  video.src =
    "https://daiz.github.io/frame-accurate-ish/time.mp4";
  video.requestVideoFrameCallback(updateCanvas);  

frameOffset must be determined from seeing what const frames = Math.round(metadata.mediaTime * fps) equals to at time = 0.

Thanks to Blog Post: https://blog.tomayac.com/2020/05/15/the-requestvideoframecallback-api/