I just observed those and well I gotta say, I don't see any difference. The only thing I can see is that on the x15 AF the yellow line on the road is more visible.
I just cant see a difference. Sorry, I tried many times before and I just can't, as hard as I try.
So I just turn it off, no AA and AF makes the game runs smoother and well if I don't see a difference. I think its the best as it can get.
Allthough I gotta say that if a my fps<50 I will notice. If you show me a video of 50 and 30 FPS I will see a difference. Thats why I happened to enabled vsync on BF3. I can't stand 30 FPS.
As of gaming in general. Even if I had a duel GTX 590 or w/e that can run BF3 on ultra settings. I would still set it to LOW on MultiPlayer. I will takeout as many stuff out of the way as possible, including explosions, smoke, blood, the tiny pieces that fly away when you blow up stuff (I forgot the name), make the gun not move when I shoot it, make the gun not show any effect what so ever when I shoot it or even remove the gun from the HUD as it serves no real purpose. Also increase the FOV to 90+. MW3 gave me a headache when I played with it, and I wasn't the only one, an FOV smaller than 90 is BS for PC gaming.
Why is that? Well that is how I play MP, I don't care about all the effects, they distract me from killing other people. When I played Wolfenstein Enemy Territory. I removed all the above. You can see videos where the HUD is just at some corner (or several) and the main focus is just what you can see now.
Now, on SP.. Thats a different league. on SP I played BF3 on Ultra settings to enjoy the game graphics as much as I can. I don't care about those bots running around, if it takes me a little longer to spot them, so be it, they are just some dumb bots and if I die I just replay the mission or checkpoint or w/e I was on. The SP on the past years is less focused about the gaming and more about the SHOW, its alot more cinematic and has more effects etc... And I think that BF3 is a great example for that.
On MP... I just wanna kill people and be a fragger
and the graphics + HUD are the first to be taken down to the minimum.