Post запрос и iframe

for (int a = 1; a <= n;a++)
            {
                WebRequest request = WebRequest.Create("http://site.ru/addnews.html");
                request.Method = "POST";
                player = "<iframe width=\"510\" height=\"400\" src=\"http://xxx.com/xembed.php?video=" + linemov[a] + "\" frameborder=\"0\" scrolling=\"no\"></iframe>";
                string postData = "title="+linetit[a]+"&alt_name=&catlist%5B%5D="+cat+"&bbfont=0&bbsize=0&short_story=[img]"+lineima[a]+"[/img]&bbfont=0&bbsize=0&full_story="+player+"&tags="+teg+"&xfield%5Bplayer%5D=&xfield%5Btime%5D=&xfield%5Bshots%5D=&allow_comm=1&allow_main=1&approve=1&allow_rating=1&add=%C4%EE%E1%E0%E2%E8%F2%FC&mod=addnews";
                byte[] byteArray = Encoding.UTF8.GetBytes(postData);
                label2.Text = player;
                request.ContentType = "application/x-www-form-urlencoded";
                request.ContentLength = byteArray.Length;
                Stream dataStream = request.GetRequestStream();
                dataStream.Write(byteArray, 0, byteArray.Length);
                dataStream.Close();
                WebResponse response = request.GetResponse();
                Console.WriteLine(((HttpWebResponse)response).StatusDescription);
                dataStream = response.GetResponseStream();
                StreamReader reader = new StreamReader(dataStream);
                string responseFromServer = reader.ReadToEnd();
                Console.WriteLine(responseFromServer);
                reader.Close();
                dataStream.Close();
                response.Close();
            }

player = "%3ciframe width=\"510\" height=\"400\" src=\"http://xxx.com/xembed.php?video=" + linemov[a] + "\" frameborder=\"0\" scrolling=\"no\"%3e%3c/iframe%3e";

player = "%3Ciframe+width%3D%22510%22+height%3D%22400%22+src%3D%22http%3A%2F%2Fxxx.com%2Fxembed.php%3Fvideo%3D" + linemov[a] + "%22+frameborder%3D%220%22+scrolling%3D%22no%22%3E%3C%2Fiframe%3E";

            string s = "<iframe width=\"510\" height=\"400\" src=\"http://xxx.com/xembed.php?video= \" frameborder=\"0\" scrolling=\"no\"></iframe>";
            s = System.Convert.ToBase64String(System.Text.Encoding.UTF8.GetBytes(s));