any observable difference between 1080 and 4k?

Mark Phelps said:

I didn't say HOW MUCH of the video was displayed on the screen. I said 1/4 of the SIZE, not 1/4 of the VIDEO.

And yeah, I know you can resize the video window but with the native size being 1/4 of the size you would see on a 1080p screen, I would think you would get a fuzzy image resizing the window to 4 times its size to fill the screen. And, if that is the case, then there is little value in having a 4K screen just to watch videos.

I don't do this on my PC monitor (which is natively 3820X2160), but on a 4k TV, scaling 1080p up to 2160p is still pretty sharp. 2:1 isn't that radical an upscale.

margrave55 said:

You won't see a difference unless the source video was shot in the higher 4k mode. There isn't much of that yet, is there? The only places I've seen it is in the stores ... where they're trying to sell 4k TVs. At home I don't have any 4k channels available. None.

There's a lot of 4k material on YouTube, including an excellent walk-around in NYC that runs about 3hrs. and 15mins.