The former U.S. secretary of state and presidential candidate said: "Well, I just want to be sure that we can beat the current president, who I think has done a lot of damage to our country and the world.
So I just want whoever gets nominated to be able to win.
That's my goal." She described the election as a "contest" and compared it to her own campaign trail.
She remained tight-lipped about who she would be endorsing in the race, winking at reporters while saying she would leave that to the voters.
Clinton took part in 35 hours of interviews with filmmaker Nanette Burstein, who collected behind-the-scenes footage during the 2016 campaign.
Both said that no topics were off limits.
Clinton, who is now 72, discussed everything from her loss to Donald Trump to her husband's infidelity that led to his 1998 impeachment.
Bill Clinton also was interviewed for the film.