Part of the sensing and diagnostic module (SDM), it is really silver with a yellow sticker, and in some cases, the information has been used to prove a person innocent. They were originally installed to prevent frivolous lawsuits against the manufacturer. You know, the ones where the person states, "I was pressing on the brake and the car did not stop." In court, the recorder shows that the person had actually been stepping on the accelerator pedal.
Over the years, they have more than paid for themselves against these types of lawsuits.
They also will record data if the air bags do NOT go off, during a near deployment.