[tambourine_man]

I didn't get it at first either. You need a DDC/CI enabled monitor, which means it can switch input via software. Plug one input on each computer.

The USB switch button will send a connect/disconnect event to both computers and they will then react accordingly.

[BoorishBears]

The button doesn't actually send an event

I wrote a similar program, you just listen for something connected to the hub disappearing

  if mouse no longer connected:

    tell monitor to switch output via DDC

  else if mouse now connected:

    tell monitor to switch back via DDC