RTMPdump has trouble parsing the "app" so it is usually best to declare it explicitly, with "-a"
rtmpdump -r rtmp://extondemand.livestream.com -a ondemand -y mp4:trans/dv15/mogulus-user-files/chredbullspace/2011/09/21/7f1610d0-ac6e-4612-95b3-6151539e7901 -o v.flv