I actually went to a Judge Mathis taping before and they talked to us and said to exaggerate for the camera. Not to necessarily fake laugh if it isn’t funny, but if something is funny, to put on for the cameras. Also that baliff isn’t a real baliff. Judge Mathis is a real judge and the cases are real.
Also, when you see the plaintiff and defendant come out, they make sure to get that right before the case even proceeds. It’s not immediate like on the show. That voiceover you hear is added in when the show airs.