Thanks! I've replaced it with your working nvidia link.
I got the citeseerx.ist.psu.edu link off google and it worked for me the first time. I'm an alum but not logged into anything, so either it was a bypass via google referrer (not sure why they'd do that, it's not looking for advertising clicks) or some usage limit.
http://research.nvidia.com/publication/interactive-indirect-... has the paper plus presentation available, plus abstract and other links.