Not sure that I understand you correctly. If I click on webcam, the leftmost menu choice, it will activate the webcam, that's it. Where do you mean I can check if it is erroneously detected?
There's a menu, Tools----> option... that gives you settings for web camera, capture device, network camera and screen capture.
In web camera settings there's a drop down list, the default choice is USB camera but it also lists a USB 2828x device which I believe is the VHS capture I'm using.
However, choosing the capture device all settings are grayed out.