NetStream - Adobe ActionScript® 3 (AS3 ) API Reference

There is also a library which assists in setting up the netstream in a way that the metadata is preserved and the boiler plate code is all setup.

https://github.com/jakehilton/netstreamsmart

This also implements a standard listener model as well as this netstream client model described in the examples. So along with setting up a listener for accessing a NetStatus event you'd also setup a listener for the onMetaData event.