Dart:如何使用Youtube数据API上传视频？

我试着用googleapis把视频上传到Youtube上，我试了一下：

    import 'package:googleapis/youtube/v3.dart';
    import 'package:googleapis_auth/auth_io.dart';
    
    final _credentials = ServiceAccountCredentials.fromJson(r'''
    {
      "private_key_id": ...,
      "private_key": ...,
      "client_email": ...,
      "client_id": ...,
      "type": "service_account"
    }
    ''');
    
    const _scopes = [YouTubeApi.youtubeUploadScope];
    
    Future<void> main() async {
      final httpClient = await clientViaServiceAccount(_credentials, _scopes);
      try {
        final youtube = YouTubeApi(httpClient);
        
        youtube.videos.insert(request, part);  //What do to here??
    
      } finally {
        httpClient.close();
      }
    }

现在我不知道下一步该怎么做了？我没有找到任何关于这方面的文档。