These dlls are needed to run VirtualDubMod.

ogg.dll and vorbis.dll are part of the OGG project by Xiph.org. They are available on http://www.vorbis.com

scilexer.dll is part of the Scintilla project available from http://scintilla.sourceforge.net

As far as I know all these files are distributed under the GPL except scilexer.dll which has the following license:

License for Scintilla and SciTE

Copyright 1998-2001 by Neil Hodgson <neilh@scintilla.org>

All Rights Reserved 

Permission to use, copy, modify, and distribute this software and its 
documentation for any purpose and without fee is hereby granted, 
provided that the above copyright notice appear in all copies and that 
both that copyright notice and this permission notice appear in 
supporting documentation. 

NEIL HODGSON DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS 
SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY 
AND FITNESS, IN NO EVENT SHALL NEIL HODGSON BE LIABLE FOR ANY 
SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 
WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, 
WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER 
TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE 
OR PERFORMANCE OF THIS SOFTWARE. 
