I recently tried to record two live bbc streams using get_iplayer command but unfortunetly the second stresm didnt start downloading and it was giving me rtmpdump error and saying closung rtmpdump!( i opened two get iplayer command line). Could any one tell me if there was problem with second stream or problem is because downloading two streams at same time not supported buy het iplayer?

You can run two instances of get_iplayer. However, recording of live streams is unreliable. It may take many attempts for a stream to start, and sometimes it may not work at all.