Question watch 4k video on 5120x1440 monitor

[TwenteMaster]

how is the feeling, will the video be stretched?

 

[RLarcosPES2]

It will look great with letterboxing. Video streching appears only on Android phones.

Ypu will just see black bars on the sides, like watching a 1440p video. I don't have a monitor like that myself, but I know that if you are using a PC it will downsample the video automatically to 2560x1440 and display it as if the video was this resolution in the first place.