It's been a while since I last had to parse ASP.NET pages, but AFAIK, the viewstate isn't meant to be parsed by clients, you just have to re-send it during postbacks. It's more like a cookie, or Rails' authenticity_token [1].
EDIT: Oh, ok. Re-reading the article, he was parsing the ViewState because there was some data hidden in there (a serious flaw actually), instead of scraping the site normally! Clever!
And accompanying source code: https://github.com/theiostream/viewstate