public/inspect-video.html

<!doctype html>
<html lang="ja">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Local video frame inspection</title>
    <style>
      html, body { margin: 0; min-height: 100%; background: #111; }
      body { display: grid; place-items: center; min-height: 100vh; }
      video { width: min(100vw, 60vh); max-height: 100vh; background: #000; }
    </style>
  </head>
  <body>
    <video id="clip" muted playsinline preload="auto"></video>
    <script>
      const params = new URLSearchParams(location.search);
      const clip = document.querySelector('#clip');
      clip.src = params.get('src') || '';
      clip.addEventListener('loadedmetadata', () => {
        clip.currentTime = Number(params.get('t') || 0);
      });
    </script>
  </body>
</html>