You can find webmdshow-0.9.9.0-20100702.zip on the downloads page:
http://code.google.com/p/webm/downloads/list
http://code.google.com/p/webm/downloads/detail?name=webmdshow-0.9.9.0-20100702.zip
http://webm.googlecode.com/files/webmdshow-0.9.9.0-20100702.zip
The source code is also available as a separate download:
http://code.google.com/p/webm/downloads/detail?name=webmdshow-0.9.9.0-20100702-src.zip
http://webm.googlecode.com/files/webmdshow-0.9.9.0-20100702-src.zip
You can also download the sources directly from the git repository:
git clone git://review.webmproject.org/webmdshow.git
Here are a few of the changes in this release:
(1) two-pass VP8 encoding is now fully implemented
(2) makewebm now supports reading and writing GraphEdit (*.grf) files
(3) source filter now uses Cues element, for more efficient seeking
(4) webmmux filter now allows you to specify WritingApp element
(5) VP8 encoder filter now allows you to force a keyframe to be
created immediately
Regards,
Matt