On the device that will be filming, got to the options screen by clicking on the Options button, and set the Remote Control setting to Camera, then return to the app's camera viewfinder.
Next, on the device that will act as a remote, set the Remote Control setting to Remote,
and return to the app's camera viewfinder.
After a brief handshake between the devices, the remote will connect and update it's settings to reflect the current parameters of the app operating as the camera. You can now operate all of the camera controls on the remote, and the filming camera will follow along.