The girl is the fifth complainant in Bell's trial, which began last week in the High Court at Whanganui.
Bell faces 32 charges of sexual offending against eight young girls, including 12 rape charges, three unlawful sexual connections, and 17 indecent assaults.
He has already pleaded guilty to one charge of indecency with another girl aged 12-16.
Yesterday's complainant had three evidential video interviews - two in 2010 when she was eight, and one in November last year.
In her first two interviews, she spoke about Bell rubbing her "privacy" with his hands on a number of occasions, telling the interviewer he had been "naughty".
She said Bell touched her and her younger sister while they were sleeping in a bed with him and some of her other siblings. She would have been about seven years old, she said.
"[He] said if I tell somebody I will be in really big trouble."
During her third interview, when she was 12, the girl told police about witnessing another young girl lying naked on top of Bell in some long grass while he was also naked.
She also said Bell pulled her and her sister's pants down on another occasion, and smacked her in the head when she held her underwear up.
The girl spoke of other alleged incidents, including Bell undressing her and pulling her on to him while he lay in a bed, and one occasion where she and her sister were in the bath and Bell came in and pulled his pants down.
She also said Bell once gave her and her sister $20 each and told them not to say anything to anyone about the alleged abuse.
Mr Steedman suggested the incident where the complainant allegedly saw another girl naked with Bell was made up, because the other girl never mentioned it in her evidence.
"I don't even care what you think because it's what I know," she replied.
She called Bell a "f***ing liar" and at times refused to answer Mr Steedman's questions.
He pointed out that during her first interview at the age of eight, she told the interviewer she had been annoyed about sleeping in a bed with Bell because of him "farting", but only mentioned later about how he had allegedly touched her.
He also questioned why she only talked about the worst of the alleged offending in the third interview, and made no mention of it in the first two, despite all of it having allegedly happened before any of the interviews took place. The trial, before Justice David Collins, continues.
