We are using a Sony SRG-X120 with a NDI license for live streaming. Our plan was to use a standard 3-axis USB joystick to control it via Studio Monitor but found that Studio Monitor is interpreting the joystick's Z-axis movement as Focus rather than Zoom. The camera responds correctly when using the virtual controls on the Studio Monitor PTZ interface. The problem arises when using an external USB joystick or controller. I've tried a CH Products Professional USB joystick, a PS4 controller, and a Logitech F310 controller similar to the one demonstrated in your YouTube video. https://www.youtube.com/watch?v=qSwVcLAJAvA. All three get the same response as does the controller used in your video.

A standard 3-axis joystick only has a X, Y, & Z-axis. X=Horizontal, Y=Vertical, Z=Zoom. It does not have a Z Rotational axis like the game controllers do. A standard game controller right joystick movement is Left/Right=Z-axis & Forward/Back=Z Rotational axis. As can be seen in the video link below, Studio Monitor is using the Z Rotational axis for zoom and the Z-axis for focus. Unfortunately this means PTZ camera control via Studio Monitor will not work with a standard joystick. If I'm thinking about this correctly I see the Z-axis as a car driving down a road toward the X/Y intersection and the Z Rotational axis is the steering wheel rotating around the Z-axis.

Intuitively the Forward/Back movement of a game controller makes sense for zoom but if Studio Monitor is to be used with professional PTZ joysticks I recommend the axis it uses for zoom be changed to the Z-axis.

I used Windows' built in Game Controller Test to demonstrate what I am seeing.