ATI vs. NvIDIA ???

[Attila]

As everyone can see, I'm an ATI user. But when I look at some COD films on YouTube i have the feeling that most of these films are of better quality than when I play! My settings are all on the highest level, but as an Example, when i'm flying north to the coast of England in an altitude of maybe 4000m the rivers looks more than lakes as than rivers! I never seen something like that in COD movies! Is this a recording thing or maybe an ATI bug, like the 3 lines on the horizont? Does NvIDIA users see the same phenomenon?
The picture is also a bit of, how can i say, a kind of grainy!