lady not laughing??

I was watching this, thought it was funny offcourse. But I noticed this lady in the front row and she doesn't laugh. Not once do I see her laughing and it really bothers me. At one point they're filming the back of her head and it looks like she's laughing because her head is moving in a way that a head moves when you're chuckling, but then when they show the front of her face there's no expression. She's also chewing gum. Anybody notice her? After i noticed her not laughing I kept studying her.
What was she doing there in the first place? And she was sitting in the front row too, why? If you don't have a sense of humor, don't go to stand-up comedy shows. And leave the front seat for people who might actually enjoy it! II wonder what WOULD make her laugh.