A flash player bug has been filed regarding a flash player bug/limitation where a 'GET' style request ignores any specified request-headers (notably, "content-type") that are added.

No errors/exceptions, and the online docs don't mention this limitation, but nevertheless, sniffing the connection (with fiddler) shows that the headers are *not* sent along as they should be. They are sent just fine with 'POST' requests, but not 'GET' requests.