. . . when talking about video resolution? I'm looking at some 720p YouTube video and man, it's stunning, maybe too sharp for me. Is there a point of diminishing returns, or will there always be a push to make things even more clear, as with audio?

I think enough is enough when the public decides it's enough.

Based on the surging sales of DVD and the lagging sales of Blu Ray, I think the public is ready to rule on this.

Noes!!!! I just got a Blu-Ray player!

Well, to be fair. I got it because my wife own a 2-disc blu-ray set of the live-action "Deathnote" movies and wants to watch them.
My anniversary is Thursday, she has Dialysis that day. When she comes home, it will be set up waiting for her.

One benefit of even higher resolution is for those who like 3d content, especially with glasses-free methods. The lenticular lenses or blocking grids actually only show half of the total vertical resolution to each eye. So if you want 720p to each eye, then double the lines are needed. Same with if you want 1080p to each eye.

The only other benefit is if you had really high resolution like 4k cinema, then you can sit a couple feet away from the screen and not see the pixels. But who would really do that...

The public HAS ruled. My Blu Ray is almost as clear as looking out my window!

a few well chosen words can often replace much show that truly reveals little more than skin pores and intimate details of oils and cleanliness.

now if you want an immersive experience - that's a combination of frame rate, resolution and field of vision.

I appreciate the market driven stuff, but I was really asking about the limits of physical visual perception--is there such a thing, and if so, what is it? That is, at a given distance and for a given size when can the human eye no longer detect a difference?

? the crenelations on a grain of pepper.
scale from there.

I'm holding out for 12d gamma-photon screen and Gold-Ray player. Why invest 4 grand in a TV that's going to be outdated before the next season of "Dexter" even starts?