Hah, I had to watch that for a while to figure out how it was relevant. I'm not sure if they'll be good enough , but i'm looking at either Vexta PK299-F4.5A or PK299-03AA (same motors, different wiring), and at least one of them double shaft. If the detent torque isn't enough to stop the Z from dropping when not under power, I'll have the option of adding a brake.
I'm not particularly impressed with the torque curve on the Vexta motors, but the Wantai and Long motors on Alibaba are lacking any torque curve info, and even the data provided is a bit inconsistent between sellers. I guess it's a case of, "better the devil you know".