Thanks. It looks just what I'm looking for. But, are you sure that integrated graphics will handle 4K@60FPS video?there are plenty very powerfull micro PC's out there most notably lenovo M tiny systems are very tiny and pack quite a punch.
But with anything tiny costs start to creep up.
https://www.lenovo.com/gb/en/desktops-and-all-in-ones/thinkcentre/m-series-tiny/c/M-Series-Tiny
i5 version such handle everything yopu need.