I've got a problem reading through from Flex a url that has Transfer-Encoding: chunked since the FLex waits for that server to transmit terminate signal which in chunked transfer is not sent...
Make use of the URLStream class rather than whatever loader you are using now. Its ProgressEvents enables you to read portions prior to the message completes.
But when you browse the documents a bit more carefully, there is a following. Therefore it becomes obvious, you need to simply check how big received portions until it get ZERO.
The information transfer is ended with a final slice of length zero