Well,
to catch the stream you need to, after the "NetConnection.Connect.Success", send the command
this._connection.call("rr", null, $decrypt);
where decrypt is the tea_decryption of the r2-property received and transformed. See
https://github.com/denobis/4od/blob/...ea_decrypt.php where i've implemented the decryption process in php.
For example, when connecting we received
r2=5n251623p7q688po5s9o89p8249so8oqs399r7os8982srs 70852662qpq14r2409r6q58r8
which is decrypted to
55a7b6f3-ba33-4596-8965-b46d2247ea51
But you need to implement this in the c-sources of rtmpdump and compile it. Funny.