Why j7 pro cant play 4k video in gallery also?

Aa gya bhai log

Dekh samsung agar oreo ka update nhi aya1 October se pahle to.. Mc walo phone Launch mat karna jisko nhi de sakte ho update.2016 wale model me update pahle aur2017 wale baith ke muh dekhe.Bsdk samsung

What happen samsung "j7" pro is not getting any update? I think you forget about this device..Sabhi phone me update aa rahe hai Isime nhi aa raha hai.. yeha tak ke security patch ka bhi update nhi de raho holast December 1 ka hi hai...Do something..

Why we cant insatll apk file of any third party appi dont know what they want to saybefore that on marshmallow i can install apkfiles but now after nougat update we cant install...see friends I have attached a photo see whathappens when i try to inst...