Despite the fact that Configuration Editor cannot be accessed while a virtual machine is running, you can connect and disconnect additional devices, switch the media they access. So, when running virtual machine you can work with the following its devices:
To connect/disconnect any device, it should be enabled in the virtual machine configuration. If you have disabled some device, it will not be included into running virtual machine.
USB Devices
If you start the virtual machine with the USB controller enabled, you may connect various real USB peripherals to the virtual machine. The USB controller itself can not be connected or disconnected.