Hello Brian,
First, it’s important you do not confuse the software titles. You wrote “when you bought the vegas pro 9 expansion pack”. ‘Vegas Pro’ is an entirely different package and I don’t even think Version 9 is released yet. I think only 8 is out there right now.
What I think you are talking about is ‘Vegas Movie Studio Platinum 9’, and this is the version that I purchased.
You also wrote “I have vegas studio 8.0 and I need to be able to do HD video, which 8 cannot”, which is not a true statement. Vegas Movie studio 8 *can* do ‘HD’ video (which I believe you mean HDV or ‘High Definition Video’). It just does not have the ability to encode (or export) in h.264. I also believe version 9 has added more support for camcorders which record in AVCHD format.
Now, the only thing I have used h.264 for is to encode movies for posting online to a website called Vimeo. Vegas Movie Studio does not make it readily apparent to export in h.264, and as a result, I followed the instructions kindly provided by Eugenia Loli which can be found on this page:
https://eugenia.gnomefiles.org/2007/11/09/exporting-with-vegas-for-vimeo-hd/
and specifically, these are the instructions for using the Sony AVC codec (which results in the h.264 mp4 file):
https://eugenia.gnomefiles.org/images/sonyavc.png
Hope this helps.
Rico.