It all depends how Jim implements the 'tapping on the glass' feature. Hopefully we'll be allowed to not just trigger it with a keyboard command but actually use the mouse to click on a certain part of the glass. I guess Jim will need a Fish mouse cursor too
A touch screen would seamlessly integrate with the mouse-click on certain parts of the tank. And the webcam, there is already software (as you linked to) which measures the changes between the last picture taken and the next and if it more than 5%, then it is assumed that someone has walked into the room. This has also been used for security purposes as you can imagine.