While I'm THRILLED that you're looking at that tutorial, I have to tell you that, while that tutorial is wonderful for Mel scripting, it simply will not work for Python. This is for a few reasons: A) It wont work (as you've already seen); B) Autodesk is still figuring out how they're implementing QT; and C) Because of that some functions don't work (no integer fields and spotty documentation). You COULD use it as a basis if you were going to layer pyQT or something else on top of it, but in the end, you're probably going to be better off creating your ui in Mel (via python) or pyQT (or one of the other QT options out there). There's a thread here that talks about python and pyQT. You might find some help with that.
When I wrote that tutorial, my focus was mainly on getting a working interface with Mel, because at the time I didn't know python. I've been writing things in Python now, but haven't made a UI for it yet, but once I do, I'll post a write up on my site about that as well. It'll be a few weeks before that happens though, so if what you're doing is time sensitive, I'd go look at the pyQT stuff. HTH.
You might check this post out as well.