问原始文件在通过Youtube API v3上传时总是“未知”的

EN

        async void Upload()
    {
        _lastBytes = 0;
        _currentItem = -1;
        for (_currentItem = 0; _currentItem < WorkList.Count; _currentItem++)
        {
            var videoSource = WorkList[_currentItem];
            UserCredential credential;
            using (var stream = new FileStream("YourJsonFile", FileMode.Open, FileAccess.Read))
            {
                credential = await GoogleWebAuthorizationBroker.AuthorizeAsync(
                    GoogleClientSecrets.Load(stream).Secrets,
                    // This OAuth 2.0 access scope allows an application to upload files to the
                    // authenticated user's YouTube channel, but doesn't allow other types of access.
                    new[] { YouTubeService.Scope.YoutubeUpload },
                    "user",
                    CancellationToken.None
                    );
            }
            var youtubeService = new YouTubeService(new BaseClientService.Initializer
            {
                HttpClientInitializer = credential,
                ApplicationName = Assembly.GetExecutingAssembly().GetName().Name
            });

            var video = new Video();
            video.Snippet = new VideoSnippet();
            video.Snippet.Title = videoSource.Title;
            if (videoSource.Description != null)
                video.Snippet.Description = videoSource.Description;
            if (videoSource.Tags != null)
                video.Snippet.Tags = videoSource.Tags.Split(',');
            video.Snippet.CategoryId = "22";
            // See https://developers.google.com/youtube/v3/docs/videoCategories/list
            video.Status = new VideoStatus();
            video.Status.PrivacyStatus = "private"; // or "private" or "public"
            var filePath = videoSource.Path; // Replace with path to actual movie file.

            using (var fileStream = new FileStream(filePath, FileMode.Open, FileAccess.Read))
            {
                _size = fileStream.Length;

                var videosInsertRequest = youtubeService.Videos.Insert(video, "snippet,status,contentDetails",
                    fileStream, "video/*");
                videosInsertRequest.ProgressChanged += videosInsertRequest_ProgressChanged;
                videosInsertRequest.ResponseReceived += videosInsertRequest_ResponseReceived;
                await videosInsertRequest.UploadAsync();
            }
        }
    }