rtmpdump for Justin.tv ?

[thefallenghost]

Hello,
I'm relatively new to rtmpdump, and I'm trying to use it manually on Justin.tv, but have not been able to as of yet.
I downloaded RTMPDumphelper and it works well on Justin.tv. So I tried to copy the parameters from the rtmpsuck window and use them with rtmpdump manually, but I get "server error".
Also, it's strange that, when I use Wireshark to get the parameters, I get all differents parameters than the rtmpsuck sindow.
I also found an application named jtv-downloader which can use rtmpdump to download streams from Justin.tv. An interesting thing is the usher token is always the same for this program for a specific stream quality, whereas the rtmpsuck (with rtmpdump helper) has a different one each time I load the stream.

Also I'm not really sure what the difference between -s and -w is as both of the aforementioned programs only provide one link for a swf player.

Many thanks!!

edit: when I try to paste the commands from the box in the Params tab of jtv-downloader I get "ERROR: Closing connection: NetStream.Play.StreamNotFound".