The real issue is that's working only for one try. When you try again you get this.
Code:
rtmpdump -r "rtmpt://213.250.3.162/" -a "" -y "hr1" | vlc -
RTMPDump v2.4 GIT-2012-03-08 (Compiled by KSV)
(c) 2010 Andrej Stepanchuk, Howard Chu, The Flvstreamer Team; license: GPL
WARNING: You haven't specified an output file (-o filename), using stdout
Connecting ...
WARNING: HandShake: client signature does not match!
INFO: Connected...
ERROR: RTMP_ReadPacket, failed to read RTMP packet header