There is actually very little in the way of conceptual graphics updates. Most of what you see in that video are new effects replacing the vanilla ones (notably: Trade Lane travel; engine FX; possibly some new textures.) This is mainly because of the limitations of Freelancer's old game engine.
Ambient lighting can be adjusted: decreasing the amount of ambient light makes it feel more realistic (ie. the light is coming from a point source, not from everywhere).
Conveniently, a mod has been made in which you can control the level of ambient lighting. It's called the Realistic Lighting Mod, and you can find it in this thread: http://discoverygc.com/forums/index.php?showtopic=96116
Check out the first download link in the first post. I have it set to 15%, and it works quite comfortably.
