cyrnel

<a href="http://virtualdub.sourceforge.net/">virtualdub</a> is good for avi's without AC3 or ASF inside.

For mpeg files, depending on what's really inside:
<a href="http://www.videohelp.com/tools?tool=Mpg2Cut2">Mpg2cut2</a>. It's free and works great.
<a href="http://www.videohelp.com/tools?tool=MPEG_Video_Wizard">Womble</a> is very nice. Trialware, but if one time is enough... Otherwise $120 retail. I think they're still giving a $50 discount.

If you need tools to help identify the contents:
<a href="http://www.doom9.org/Soft21/Editing/gspot221.exe">gspot</a> the old standard for exposing avi's.
<a href="http://www.kcsoftwares.com/index.php?vtb">KC Video Inspector</a> isn't as direct, but it handles more types including MPEG-2 & QT.

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There are a vast number of people who are uninformed and heavily propagandized, but fundamentally decent. The propaganda that inundates them is effective when unchallenged, but much of it goes only skin deep. If they can be brought to raise questions and apply their decent instincts and basic intelligence, many people quickly escape the confines of the doctrinal system and are willing to do something to help others who are really suffering and oppressed." -Manufacturing Consent: Noam Chomsky and the Media, p. 195