Please don't specify the options in that manner, support for that style will be dropped in a future release.
Code:
rtmpdump -r rtmp://bbcmedia.fcod.llnwd.net --playpath 'mp4:iplayerstream/secure_auth/1500kbps/b000mmn8dh264_high_151437436?s=1270954121&e=1271040521&h=40203b7239a2737444b250888b79ed7e' --swfUrl http://www.bbc.co.uk/emp/10player.swf\?revision=14200_14320 --app 'a1414/e3' --timeout 10 -o '/dev/shm/iplayer_streaming_h264_flv_high.flv'