Most people that are using RTMP are using it to serve static files that they want to make harder to copy than downloading an FLV file. As I recall, the problem

Most people that are using RTMP are using it to serve static files that they want to make harder to copy than downloading an FLV file. As I recall, the problem with rtmpdump wasn't that it implemented RTMP, but that it included ways to bypass the "security measures" that are built-in to RTMP. It was able to spoof all of the parameters that FMS uses to determine whether or not it should serve a stream, and would save a copy of the video to disk instead of just displaying it to the user.