Error 403 means "Access Forbidden". probably they are checking user-agent in request header and denying access to rtmpdump. however you can bypass it by manually fetching the player.swf and hashing it or just put the following in your .swfinfo file.
Code:
url: http://www.livestation.com/flash/player/5.4/player.swf
ctim: Sat, 07 May 2011 13:36:52 GMT
date: Sat, 07 May 2011 03:37:45 GMT
size: 000184ce
hash: 024c6120068144803edd17fd77456a35d1496b4490a489244efbfb6dfaccbd07