This is a television special of pickpockets in the Paris Metro. While the entire pickpocket video is in French, you will see many young pickpockets to give you an idea how they blend in crowded Metro subway cars.
The below video shows very young female pickpockets. Notice when they see they are being filmed, they cover their faces. Also, watch when the go to get onto the metro train car, the fellow passengers will not let them come in. They can tell they are pickpockets and do not want them in their car. Keep an eye out for groups of young girls or boys like this.