Never ape an Apeman

The apeman turns up on the scene

Daphne's Uncle John has invited the gang to be extras in his next film. However, the Apeman interrupts the next scene. The female lead is saved by Scooby, but then quits until the Apeman is gone, and Carl, the Star, is locked in a trunk. The Gang offers to solve the mystery, and discovers the mystery of the Apeman legend... 7/10, simply because Fred gets thrown into a secret door, which has occured only ONCE in my memory.