artoolkit no webcam showing

[vrmdl]

I tried the following to test the webcam

*****
import viz
viz.go()

#Create Video Camera extension
video = viz.add('VideoCamera.dle')

#Connect to next available generic video capture device
cam = video.addWebcam(size=video.WEBCAM_MAX_SIZE, id=1)

#Create quad to display video capture data
quad = viz.addTexQuad(pos=(0,1.8,2),texture=cam)
***********
I noticed that I have to use "id=1" to obtain webcam image. There are two imaging devices on my computer, one is scanner, the other is webcam.

Now my question is
(1) Do I need a full license to run artookit?
(2) How do select the other imaging device in the artoolkit example I gave in the above example. I tried to use "id=1". But the function ar.addWebCamera() does not take the attribute id.

Any hint is appreciated.