Yes ( as long your PC has at least two USB controllers).
When you have connected Ubi sensor to your PC and are interacting with your display, you can still use a document camera or a Skype webcam.
You should be able to connect to the document camera and webcam as usual. However in some rare cases, Ubi will show an error that sensor is disconnected or the webcam/document camera will report that is it not available for connection.
This is mainly because of a limitation in your USB connections. Each USB slot on your computer is a port. In some computers all these ports are connected to a single controller. In some other computers, you may have multiple controllers.
In general, Ubi sensor and webcam/document cam should be on different controllers ( not just different ports) for them to work together.
Now, to make sure this is the case, please do the following.
First of all, please download this zip file, extract to any folder. The extracted folder should have a single file called usbview.exe . Click and run it.
1. Verify that your PC has multiple controllers.
When you run usbview.,exe, on the left pane of the window that pops up, you should see something like this.
As you can note, it lists all the USB controllers that are on my PC. Apparently I have three. If you see only one, tough luck. Your PC cannot have two USB cameras connected to it at the same time.
2. Make sure that each device is connected to a different controllers.
Connect Both Ubi sensor and your document camera/webcam to your PC. Run usbview,exe. On the left pane of the window as shown above, you will see a lit of your USB controllers and the devices connected to each one of them. You should see two devices called "USB Composite Device" . Make sure, each of them are listed under a different controller. If they happen to be at the same controller, unplug one of them and reconnect it to another port. Keep doing this until, you got each device listed under a different controller.