This video (at 4:39) shows how it can be done with fairly standard screen grabbing feature: http://www.pbs.org/wgbh/pages/frontline/digitalnation/learning/schools/how-google-saved-a-school.html
If, on the other hand, the student had a program like Photo Booth or Skype and in use, the school administrator would have been able to see what the webcam saw. The court filing does not seem to state with any authority what software or system was used.
(I think I'll go wash my mind out with a good Vodka at this point)
In Soviet Russia, your mind washes the Vodka out!
The Slashdot cliché trifecta is now complete.
I feel enormously sorry for the kids of the guys involved, who may forever have that site appear when they Google their dads.
One could imagine that there exists an optimal way to switch from application to application, window to window. Neither OS has it perfectly, but in both trying to better themselves, they end up looking remarkably similar.