The video, posted Friday, got more than 165,000 views, media reports said.
It shows the woman — since identified as Jamie Carillo, 28 — talking by phone with her former teacher and confronting her about alleged abuse that took place when Carillo was 12.
The former teacher, who hasn't denied the accusations, resigned as vice-principal at Alhambra High School later the same day, the Pasadena Star-News reported on its website.
The abuse is alleged to have taken place at a middle school in Riverside, Calif.
All of the communities are near Los Angeles.
School officials said the teacher resigned after an interview with administrators, the Star-News says.
Carillo, who now has children of her own — including a daughter of about 12 — told a news conference she had previously told no one about the abuse, the Star-News said. Her concern was that the teacher might abuse other children.
Civil action expected
Carillo said she had been threatened by the teacher at the time.
"She told me that she would embarrass me in front of my friends and family, and tell them I'm a lesbian and that I did stuff with her," the Star-News reported Carillo as saying.
Carillo is expected to launch a civil action against her former teacher, since the statute of limitations on the offences involved appears to have passed, media reports said.
Carillo's lawyer, David Ring, said the former teacher had been investigated by both school and law enforcement authorities in 1999 amid rumours of abuse, but there were no arrests, charges or disciplinary action, the Los Angeles Times reported.
The teacher was allowed to resign with a positive recommendation, the lawyer said.