Проблема решена
void DownloadFile()
{
setCookieContainer();
var request = (HttpWebRequest)WebRequest.Create("http://tr.anidub.com/engine/download.php?id=14012");
request.Proxy = null;
request.CookieContainer = cookieContainer;
request.Method = "POST";
request.Referer = "http://tr.anidub.com/anime_tv/anime_ongoing/9671-polnoe-zatmenie-chernye-metki-total-eclipse-schwarzesmarken-01-iz-25.html";
request.ContentType = "application/x-bittorrent";
using (var response = (HttpWebResponse)request.GetResponse())
{
Stream str = response.GetResponseStream();
byte[] inBuf = new byte[100000];
int bytesReadTotal = 0;
FileStream fstr = new FileStream("test.torrent", FileMode.Create, FileAccess.Write);
while (true)
{
int n = str.Read(inBuf, 0, 100000);
if ((n == 0) || (n == -1))
{
break;
}
fstr.Write(inBuf, 0, n);
bytesReadTotal += n;
}
str.Close();
fstr.Close();
}
}