Yes... R129 has a hydrolic pump that throws the bar up in a fractions of a second in case of emergency.
An accelrometer under the rear seat detects combined vertical, lateral, and twisting movement force (indicating roll over) and sends the order to the hydrolic system to pop the bar above the passenger's heads (as quick as the airbags deploy).
If i remember correctly, this system is disabled when the hard top is on, so if i am not mistaking, the removable hard top takes all the credit for the amazing peroformance we saw in the video...