Turn on the wireless camera and set the receiver very close to the trigger point of the PASCO track.  This will give a good picture with very little interference.  The camera is in the frame of reference of the cart which allows you to view the ball as it travels upward and then down when triggered, all while the cart is traveling horizontally.  

The audience is in a frame of reference outside of the cart and therefore they see the ball travel a parabolic arc when triggered while the cart is traveling horizontally.