There are four RTMP Flash stream recorders. None of them is perfect, so you should try all of them.

In theory FLV Recorder should be able to capture packets coming to your flash player even if the stream is protected. However it doesn't work for me. Even if it does, it produces unplayable .@@@ file. Anyway it is worth trying it.

Hopefully other developers will offer the same way of capturing RTMP streams that FLV Recorder has, and hopefully it will be much more reliable.