Html IFrame tag is not being interpret in email body

I need to send a html file(which contains a iframe) inside a email body.The html file is working fine in a browser and playing a video.But when i send it inside email body,iframe tag is not getting interpreted so does not show in the body.
This is html file.

Aman
<iframe height="390" frameborder="0" width="640"
src="http://www.youtube.com/embed/Sf5T5KjMpJU?wmode=transparent"
title="YouTube video player"></iframe>

Email body only displaying a "Aman" in bold.This is C# code.

StreamReader reader = File.OpenText("C:\\Users\\Girish\\Desktop\\amrit\\Jeff_Project\\indeex.html");
   string getemail = textbox_email.Text;
   System.Net.Mail.MailMessage message = new System.Net.Mail.MailMessage();
   message.To.Add(getemail);
   message.Subject = "Hello";
   message.From = new System.Net.Mail.MailAddress("sendingemail");
   //message.Body = "This is message body";
   message.IsBodyHtml = true;
   message.Body = reader.ReadToEnd();
   System.Net.Mail.SmtpClient smtp = new System.Net.Mail.SmtpClient("smtp.gmail.com");
   smtp.Credentials = new System.Net.NetworkCredential("sendingemail", "password");
   smtp.EnableSsl = true;
   smtp.Send(message);
   Response.Write("Sent");

Why iframe is not being interpret?Am i missing anything?

Please help and provide solutions.

Thanks in advance.

Tags: C#, ASP.NET, Email, IFrame