This comes from the man pages ...
MPEG-1 RTP .
gst-launch rtprecv media_type = mpeg1_sys! mpegdemux name = demuxer! { ! mpeg2dec! xvideosink} {demuxer.! ! ! osssink}
gst-launch filesrc location = mpeg1system.mpeg! mpegparse! rtpsend ip = IPorHostname