title: Generate thumbnail for Flutter web video files
body: <p>I'm making a video player, for which I am selecting a video and trying to generate a thumbnail to show.</p>
  <p>I'm using the following code to pick Images/videos from the file picker.</p>
  <pre class="lang-dart prettyprint-override"><code>import 'dart:html' as html;
  
  startWebFilePicker() async {
    html.InputElement uploadInput = html.FileUploadInputElement();
    uploadInput.multiple = true;
    uploadInput.draggable = true;
    uploadInput.click();
  
    uploadInput.onChange.listen((e) {
      final files = uploadInput.files;
      final file = files[0];
      entryFile = file;
      String mimeType = lookupMimeType(file.name);
  
      mime = mimeType.split('/')[0];
  
      fileType = mimeType.split('/')[1];
      baseName = file.name;
      final reader = new html.FileReader();
  
      reader.onLoadEnd.listen((e) {
        _handleResult(reader.result);
      });
      reader.readAsDataUrl(file);
    });
  }
    
  </code></pre>
  <p>How can I generate a thumbnail using the video file picked?</p>