Perhaps the problem isn't the BigScreen, it's the youtube video?

I normally run applications maximized on my 28" 4k, unless I need input from 2 applications at the same time, then I tile them.

Working from my work-issued 16" Macbook Pro or any other of my laptops is a pain because of the limited estate - it's hard to see patterns at a glance or get the whole context when I can only see 30 lines of text that is truncated at <=80 columns. Plus, the fact that the keyboard isn't detachable from the screen forces bad habits on the posture.