I know this is a longshot but I was wondering if anyone knows if this is possible.
['https://Stackoverflow.com/questions/328753', 'https://Stackoverflow.com', 'https://Stackoverflow.com/users/-1/']
Most browsers set the [HTTP\_REFERRER](http://en.wikipedia.org/wiki/Referer) header to the current URL when requesting a linked document. However, it can be spoofed so don't use it for security.
I reckon this is rather late, but since I was searching for the same information 3 years later, here it goes.

[LoaderInfo.loaderUrl](http://help.adobe.com/en_US/FlashPlatform/reference/actionscript/3/flash/display/LoaderInfo.html#loaderURL) should give you the information you are after.

HTH!