I just read about this at Xbit-labs. Hopefully both nVidia and ATI find a way to fix this problem. And otherwise we will just have to wait for the nex gen of 3D cards, or play the game without AA , it looks damn pretty without it in the videos though
I wrote an e-mail to Valve asking why they decided to keep AA off for the videos and here is what they had to say:
There are problems with the way that current hardware implements FSAA. If you enable it, you will see a lot of artifacts on polygon boundaries due to the way that they sample texture subrects with FSAA enabled. We are working with the harware companies and the DirectX team to make sure that future hardware doesn't have this problem.
1) Is this a problem that can be fixed with new drivers, or would we have to buy a whole new card to recitify it? If so, are there any cards on the horizon that would offer it?
Drivers aren't likely to fix the problem, with the exception of the ATI 9500-9800. There's hope there for being able to use FSAA properly. You are out of luck on NVidia unless either NVidia or us come up with some clever way of solving this problem.
2) Is this a problem unique to hardware + Source?
It's a problem for any app that packs small textures into larger textures. The small textures will bleed into each other if you have multisample FSAA enabled. The best thing to do right now is either buy an ATI card in the hopes that it will be solved there, or wait until the next generation of cards come out.