loading youtube iframe api with require.js !async plugin

I have a little trouble loading the YouTube Iframe API using the !async plugin, any help appreciated!

The maps example works, so I am currently assuming the basic setup must be ok:

define('something', [
'async!http://maps.google.com/maps/api/js?sensor=false'
], function () { console.log('loaded..'); } 
);

// doesn't work
define('something', [
'async!https://www.youtube.com/iframe_api!callback'
], function () { console.log('loaded..'); } 
);

// doesn't work
define('something', [
'async!https://www.youtube.com/iframe_api!onYouTubeIframeAPIready'
], function () { console.log('loaded..'); } 
);

// doesn't work
define('something', [
'async!https://www.youtube.com/iframe_api'
], function () { console.log('loaded..'); } 
);

They all get me the Uncaught Error: Load timeout for modules: async!https://www.youtube.com/iframe_api!onload_unnormalized2,async!https://www.youtube.com/iframe_api!onload http://requirejs.org/docs/errors.html#timeout or similar (depeding on setting after the second !) which probably means the callback function onYouTubeIfraneAPIready() is never called or the !async plugin doesn't know about it.

which probably means the callback function is never called. If I defined the callback function myself it works.. but still getting the timeout error.

window.onYouTubeIframeAPIready = function () {
console.log('youtube api usual callback');
}