In the video released by Clinton on Twitter, 1996 Miss Universe Alicia Machado accused the Republican presidential candidate of making derogatory comments and pressuring her to lose weight when he ran the pageant. Machado had already accused Trump on the television program "Inside Edition."
At the first presidential debate Monday night, the Democratic nominee had criticized Trump for calling Machado "Miss Piggy" and a "Miss Housekeeper."
Clinton's campaign did not immediately respond to CNBC's request for comment.
Trump said Clinton failed to get under his skin during the debate, except "maybe" after she brought up the former Miss Universe.
On Tuesday morning, Trump spoke to "Fox & Friends" about Machado without mentioning her name.
"She was the worst we ever had, the worst, the absolute worst. She was impossible," he said.
And the GOP nominee criticized Clinton about her performance.