Hidden camera in the room of sister

Brother and sister have a very bad relationship. They are constantly looking for compromising evidence on each other, and the brother installed a hidden camera in her room so that there was something to complain about. But looking at the notes later, he did not think that he would be so excited that he would have to masturbate his cock. It turns out, as soon as everyone leaves the house, the sister actively masturbates, wriggling on the bed.