If you wonder what where the hell the atrocious __doPostback, __EVENTTARGET, and (gag) __VIEWSTATE come from... the answer is .NET WebForms.
Yeah, I ran into that brickwall on one of my scraping tasks. Kudos to @dancow for finding a way around it.
Eww, glad I didn't have to with HTML that nasty. I actually coded something very similar to this (http://www.reflector.com/jail-bookings) for our website about a year ago.