Embedding comments issue

Product Support
4

I think there is a problem here.
I get the same errors and I have tried everything I could think of, I am 99.999% sure my set up is correct.
I am using v1.4.0.beta3 +99 1.4.0.beta3
Both machines are using SSL and using add_header Strict-Transport-Security, I initially suspected that SSL must be doing something strange, but seems to be unrelated.

Those guys say that v1.4.0.beta1 seems to be working, but I dont know how to downgrade yet.
Discourse is running on https://forum.domain.com
my test site is running on https://webdev.domain.com

my sample index page has

<!DOCTYPE html>
<html>
<head lang="en">

    <script src="jquery.js"></script>
    <meta charset="UTF-8">
    <title></title>
</head>
<body>

<h1>Hallo World!</h1>
<h2>How are you?</h2>

<div id="discourse-comments"></div>

<script type="text/javascript">
  var discourseUrl = "https://forum.domain.com/",
      discourseEmbedUrl = 'https://webdev.domain.com/discourse-embedded-test/index.html';

  (function() {
    var d = document.createElement('script'); d.type = 'text/javascript'; d.async = true;
      d.src = discourseUrl + 'javascripts/embed.js';
    (document.getElementsByTagName('head')[0] || document.getElementsByTagName('body')[0]).appendChild(d);
  })();
</script>


</body>
</html>

embeddable hosts: webdev.domain.com

I have not set (Although I have tried):

feed polling enabled
feed polling url
embed category

Perhaps I am omitting something really stupid