How can I pipe between two separate console application running in different console windows?

e.g. I would like to do something similar to:

ffmpeg -i 0.flv -vcodec mpeg4 -f asf -s cif - | vlc -

However, I would like to do this from two separate windows, which doesn't work, I guess this is because standard out is local to cmd windows.

cmd window 1:

ffmpeg -i 0.flv -vcodec mpeg4 -f asf -s cif -

cmd window 2:

vlc -

Is there any way to programmatically achieve this? What exactly does | do behind the scenes?