Yep thats exacty it. But any version of VD works, just set Audio to Direct Stream Copy and then Save WAV but it will actually be it original for, in your case AC3.

I mention in the Tute the use of BeSwet. AC3 Machine must have BeSweet installed and pointing to it or else it wont work. BeSwet actually does all the work, AC3 is just a fancy menu really. Its just a front end to the commandline BeSweet. Same as BeSweet GUI is a front end to BeSweet.