It is not possible to switch only video without keyboard and mouse (console) but you can independently switch the USB peripheral port instead. 

If you connect the mouse and keyboard on the peripheral ports and follow the below you should be able to achieve your requirements: 

For manual port selection: 

- To bring only the KVM focus to a computer， press the Mode pushbutton twice (the Mode pushbutton’s KVM icon lights up)， and then press the port selection pushbutton that corresponds to that computer. The port’s KVM icon (the port number) lights up. 

- To bring only the USB focus to a computer， press the Mode pushbutton four times (the Mode pushbutton’s USB icon lights up)， and then press the port selection pushbutton that corresponds to that computer. The port’s USB icon lights up