Poner boton de suscripcion de youtube en un popup en Blogger

<script src="https://apis.google.com/js/platform.js"></script>
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap.min.css">
<script src="//code.jquery.com/jquery-1.12.0.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/js/bootstrap.min.js"></script>
<script>
   $(document).ready(function()
   {
      $("#mostrarmodal").modal("show");
   });
</script>

<div class="modal fade" id="mostrarmodal" tabindex="-1" role="dialog" aria-labelledby="basicModal" aria-hidden="true">
   <div class="modal-dialog">
      <div class="modal-content">
         <div class="modal-header">
        <button type="button" class="close" data-dismiss="modal" aria-hidden="true">&times;</button>
            <h3>Cabecera de la ventana</h3>
     </div>
         <div class="modal-body">
           <div class="g-ytsubscribe" data-channel="atitedigotv" data-layout="full" data-count="default"></div>
     </div>
         <div class="modal-footer">
        <a href="#" data-dismiss="modal" class="btn btn-danger">Cerrar</a>
     </div>
      </div>
   </div>
</div>