how to download wmv&mov file by "Response.ContentType"?

My code:
          string xpdlpath = Server.MapPath("");
          string strFile = xpdlpath.Substring(0, xpdlpath.Length - 7) + "/upload/clients/" + Request["file"];
          FileStream fs = new FileStream(strFile, FileMode.Open);
          byte[] bytes = new byte[(int)fs.Length];
          fs.Read(bytes, 0, bytes.Length);
          fs.Close();
          Response.Clear();
          Response.ClearHeaders();
          Response.Charset = "GB2312";
         ...