public static System.IO.Stream DownloadFile(
     IAuthenticator authenticator, Google.Apis.Drive.v2.Data.File file)
    {
        if (!String.IsNullOrEmpty(file.DownloadUrl))
        {
            try
            {
                HttpWebRequest request = (HttpWebRequest)WebRequest.Create(new Uri(file.DownloadUrl));
                authenticator.ApplyAuthenticationToRequest(request);
                HttpWebResponse response = (HttpWebResponse)request.GetResponse();
                if (response.StatusCode == HttpStatusCode.OK)
                {
                    return response.GetResponseStream();
                }
                else
                {
                    Console.WriteLine(
                        "An error occurred: " + response.StatusDescription);
                    return null;
                }
            }
            catch (Exception e)
            {
                Console.WriteLine("An error occurred: " + e.Message);
                return null;
            }
        }
        else
        {
            // The file doesn't have any content stored on Drive.
            return null;
        }
    }