If your video card advanced settings has anti-alias set to "override application settings", then that's what will happen. If you set it to "application controlled", then you should see a difference in-game when you change the settings in-game.
You need to download and install the hi-res texture pack to see any difference in textures when you set them to 1024 or 2048.
If you normally fly with low anti-aliasing and record film, you can change the settings before running the film viewer to set up the game engine to use the higher quality settings. You may encounter stuttering and skips if you system can't handle it, but then you're not actually flying at that point.