What Steffen is referring to is the ability to change the redirect based on a field selection. So if you put a drop down in your form that said "What asset do you want?" with 30 options, you could designate which PDF to redirect to based on that.
However, what I think Dave is saying, is that he doesn't want a drop down with 30 options, he just wants to use the same form over and over and define a different thank you page based on where it's living.
As far as I know, you can't do this with a Form 2.0 embed. With Form 1.0, you had to create a unique landing page for each asset and you could reuse the form. With Form 2.0, it's the opposite. You need a unique form instead.
However, you might be able to alter the redirect using the API/jQuery: http://developers.marketo.com/documentation/websites/forms-2-0/ (take a look at the second example)