To use the FLVStreamer tool to extract an RTMP stream you need to know the rtmp address of the target stream. Once you have that change directory to the install directory of the FLVStreamer and write the following commands:

$ ./flvstreamer-1.7_ubuntu_jackalope -r 'rtmp://[IP address or host name]: [port]/river/alpha/sample1.f4v' -o testdump.f4v

It was delightful to see that the utility could also retrieve *.f4v files. I guess this means that any H264 encoded file is extractable
. The same commands work for the rtmpdump tool.