There's another stream of the Rock Werchter festival over at Skynet.de that's going to contain live audio and video (apparently the other one will be audio only) of the NIN performance. Unfortunately, they'll only be streaming 2 or 3 songs, so it's a trade off between which format you'd rather expose yourself to.*Update*
Forget all that. The stream is now available on the main Rock Werchter festival site
. Just go there instead.
The site is fairly easy to navigate, but again, it might be best to check that you have all the right plugins for your browser before the whole thing goes live.