Ajax request works in safari, but not in Firefox (Vimeo oembed)

I'm trying to get a vimeo embed code via the oembed API (json).

It works fine in safari, but in Firefox, it seems that the json returned is not interpreted correctly, as I get a null value instead of the javascript object (in the success method).

i'd give a link to a jsfiddle example, but the sample doesn't work there, some error about an unallowed origin..

So here is the code:

   <script type='text/javascript' src='http://code.jquery.com/jquery-1.4.4.min.js'></script>


  <script type='text/javascript'>
  //<![CDATA[ 
  $(window).load(function(){
  $.ajax({
    url: "http://vimeo.com/api/oembed.json?&format=json&url=http%3A//vimeo.com/2197639",
    dataType: "json",
    success: function(data) {
        $('#output').html(JSON.stringify(data));
    },  
    error: function(errorSender, errorMsg) {
        console.log(errorSender);
        console.log(errorMsg);
        $('#output').html(errorSender + ' ' + errorMsg);
    } 
    });
  });
  //]]> 
  </script>

Any ides what could be wrong? Is it something with the json?

Sample json is:

{"type":"video","version":"1.0","provider_name":"Vimeo","provider_url":"http:\/\/vimeo.com\/","title":"Early Morning Qena","author_name":"Oliver Wilkins","author_url":"http:\/\/vimeo.com\/offshoot","is_plus":"1","html":"<iframe src=\"http:\/\/player.vimeo.com\/video\/2197639\" width=\"1280\" height=\"720\" frameborder=\"0\" webkitAllowFullScreen allowFullScreen><\/iframe>","width":1280,"height":720,"duration":229,"description":"Early morning in Quft, near Qena. Shot开发者_JAVA百科 with EX1 and Letus Extreme 35mm DOF adaptor.\n\nwww.offshoot.tv\n","thumbnail_url":"http:\/\/b.vimeocdn.com\/ts\/271\/854\/27185484_640.jpg","thumbnail_width":640,"thumbnail_height":360,"video_id":2197639}

You need to use JSONP because you are trying to perform a cross domain AJAX call. It looks that vimeo supports it. You just need to specify a callback by modifying your url (notice the callback=? parameter that I appended at the end and the format=jsonp):

$.ajax({
    url: "http://vimeo.com/api/oembed.json?format=jsonp&url=http%3A%2F%2Fvimeo.com%2F2197639&callback=?",
    dataType: "jsonp",
    success: function(data) {
        $('#output').text(JSON.stringify(data));
    },  
    error: function(errorSender, errorMsg) {
        $('#output').text(errorSender + ' ' + errorMsg);
    }
});

and here's a live demo.