Yes, even downsampling (1080p -> SR 4k -> Spline64 1080p) a Blu-Ray does not show any noticable difference. So it's not only because of YouTube.
I tried this today when experimenting for a project, but with AOTC:
http://screenshotcomparison.com/comparison/123910
Best results are at the weapon's scope. Overall it introduces banding at gradients through more random noise, take a look at the edges of the first soldier's hat. Although AOTC and that frame might not be the ideal test subject.