Like many channels it used to just be a 'second channel' for lower quality/didn't make the cut/not expected to be popular sort of videos, at least by my viewing and understanding. But more recently his 'main' channel has focussed on the woodworking, and random stuff has been almost entirely the experiments (sometimes bridging the gap with woodworking, like testing woods or glues in various ways), electronics, etc.
Not to say the main channel isn't great, just only if you're into watching woodworking on YouTube perhaps, whereas I think most people reading HN comments would generally enjoy 'random stuff'.