how would I display a buffering animation whilst a netsream object was downloading video data? using Actionscript 3.0 in Flash.
Add an event listener for NetStatusEvent.NET_STATUS to the NetStream object, then use event.info to get the actual status, and react to either "NetStream.Buffer.Empty" or "NetStream.Buffer.Full".
There is a "how to use" example on the documentation page I linked to, which you can use to get started.