rtmpsuck not working using OS X - Audio/video stream recording forums

I have been desperately trying to get rtmpsuck to work on my Mac but regardless of what I do I can't get it work. I created a new user 'RTMP' and enter

Code:

sudo ipfw add 40 fwd 127.0.0.1,1935 tcp from any to any 1935 not uid RTMP

into Terminal. I then enter

Code:

sudo -u RTMP -s

and start rtmpsuck from Terminal. I then go to video on the web but instead of giving me any information it hangs my computer and I have to force a reboot using the power button. Am I doing something wrong? I'm using 2.4, would 2.3 work? Please help! :(