Quantasia told YouTube vlogger Miss Jacob Kohinoor that she filmed her alleged sexual encounter with the R&B star and that he knew she recorded it.
Sharpton is being represented by celebrity attorney, Lisa Bloom, who has been attempting to subpoena hotel surveillance video footage.
While Sharpton is one of three people accusing Usher of exposing them to herpes, she is the only one doing so publicly and has said that she is speaking out to protect anyone else that might be affected, even though she has tested negative for the sexually transmitted disease.
To the benefit of Sharpton, last month an ex Days Inn employee confirmed that they indeed saw the 36-year-old singer to at the hotel on the same night Sharpton claims they slept together.
Sharpton - who does not have herpes - recently claimed she took action against the Confessions singer for not disclosing that he allegedly had the infection because she felt her "rights were violated".
Usher has denied these claims, TMZ reported.
The host repeatedly asked Quantasia if what she was saying was true, and Sharpton said "yes", every time.
A lawsuit has been filed against Usher in Los Angeles Superior court.
Sharpton is several people to come forward accusing the "Let It Burn" singer of exposing or infecting them with the STD.
And the woman urged Usher to speak out and confirm whether or not he has the condition.
In early August, Sharpton gave a press conference where she said she would never have had sex with Usher if she had known he was infected. Bloom has said that at least one of them does have herpes.
Things just went from bad to worse for Usher. The suit alleged that he was diagnosed with herpes in 2009 or 2010.
Usher's other two accusers - a man and a woman - have so far chosen to remain anonymous.