Usually only if I'm looking specifically for aliasing issues since i'm used to looking for that sort of artifacting for work. Otherwise, I generally ignore 4k. I still only use a 1080p tv and use 1440p monitors. I have no desire to exert have 4k monitors and no need for a 4k tv
Yea, I can tell the difference but its not a big deal. I certainly wouldn't pay more for one but you cannot buy a standard 1080p tv easily where I am from. The TV I just bought has a decent upscaler so standard 1080p looks almost as good as standard 2160p(4k as they call it.) HDR10 applied to either 1080p and 2160p(4k) is a far better upgrade to me in movies and the one game I tried it on(Far Cry 5).
On this crappy little screen? I don't have enough pixels to see any difference. Only thing I notice is the download time.
I guess you need a huge screen to notice the difference. But then, everything is streamed and it takes a lot more bandwidth. Honestly, meh.
4k version of the video instead of the normal 1080p. 4k has four times the number of pixels.
You'll need a 4k Bluray player and 4k TV to be able to see all the details.
I haven't messed with them but you should still be able to play the 4k disk on a regular Bluray player, but it would play the normal HD version of the video.