$ postproc -shrink 1.5 World\ Race.mpg.tovid_encoded.mpg World\ Race.mpg.tovid_encoded.postproc_shrunk.mpg
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postproc
Video postprocessing script
Part of the tovid suite, version 0.30
http://www.tovid.org
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Gathering file information. This may take a while.
Dumping audio and video streams with the following commands:
mplayer "World Race.mpg.tovid_encoded.mpg" -quiet -dumpaudio -dumpfile audio_dump
mplayer "World Race.mpg.tovid_encoded.mpg" -quiet -dumpvideo -dumpfile video_dump
=========================================================
Shrinking video stream by a factor of 1.5
tcrequant -i video_dump -o video_shrink -f 1.5
Video stream was shrunk by 3%
=========================================================
Multiplexing audio and video streams with the following command:
mplex video_shrink audio_dump -o "World Race.mpg.tovid_encoded.postproc_shrunk.mpg" -V -f 8 
=========================================================
Cleaning up...
removed `video_shrink'
removed `video_dump'
removed `audio_dump'
Done. Thanks for using postproc!
hagabard@opal:~/Shared/tovid $ ls -lh World*
-rw-r--r--  1 hagabard      445 2.0G Mar 14 08:08 World Race.mpg.tovid_encoded.mpg
-rw-r--r--  1 hagabard      445    0 Mar 16 12:01 World Race.mpg.tovid_encoded.postproc_shrunk.mpg