Zack and Miri Make a Porno

Zack Brown and Miri Linky are roommates in Monroeville, Pennsylvania (a Pittsburgh suburb). They have been friends since the first grade. Despite Miri working at the local shopping mall and Zack working at a coffee shop, they have not paid their utility bills in months, with Zack devoting much of his free time to a fanatic following of the Pittsburgh Penguins and his status in the community amateur hockey team, the Monroeville Zombies. After work, their water gets turned off before they go to their high school reunion.
At the reunion, Miri attempts to seduce her attractive former classmate Bobby Long, while Zack strikes up a conversation with Brandon St. Randy, who reveals that he is a gay porn star, and Bobby's boyfriend. After returning home from the reunion, the apartment's electricity is turned off. Inspired by a successful viral video that was filmed by a pair of teenage boys as Miri changed in Zack's place of work for the reunion (revealing that she wore unattractive "granny panties" underwear), and emboldened by the cultural mainstreaming of pornographic entertainment, Zack convinces a reluctant Miri that they should make a pornographic film to earn money.
Gathering a group of acquaintances and hired help as the cast and crew, they decide to film a pornographic Star Wars parody, entitled Star Whores. Delaney, the film's producer and Zack's co-worker, rents film equipment and a building to use as a studio. When they return to the studio after the first night of filming, the building is being demolished, with all the equipment and costumes inside. They are told that the man that rented it to them had run off with the money. Later at the coffee shop where Zack works, he realizes that his boss threatened to install a hidden camera, which Zack finds and decides to use to replace their lost film equipment. Zack retools his film to take place in the coffee shop, revamping the film to one with a coffee shop motif, Swallow My Cockuccino. The group shoots the film after hours.
Despite their insistence that they would not let sex with each other affect their friendship, Zack and Miri soon develop romantic feelings for each other. When it comes time for Zack and Miri to have sex on camera, they find that instead of the clinical sex enacted by the actors in the other scenes, their interlude is romantic and heartfelt. Later the next evening, Zack and Miri are at home tentatively about to discuss their reactions to the scene, when suddenly their apartment's electricity and water service return. The rest of the actors and crew reveal that they pooled their resources to pay one month of Zack and Miri's bills and are throwing them an early wrap party.
At the party, one of the other actresses, Stacey, asks Miri if it's okay for her to ask Zack to have sex, since she's nervous about her upcoming scene with him. Although Miri has realized that she has developed feelings for Zack, she tells Stacey it's okay to ask him. When Stacey relates this to Zack, the two retreat to Zack's bedroom, much to Miri's dismay.
The next evening, Zack is preparing to film a scene between Stacey and another actor, Lester, that was supposed to have been with Lester and Miri. Zack is dismayed when Miri shows up and insists on shooting the scene as originally planned. In the back room, an incredulous Zack asks if she is doing this as a form of retaliation, pointing out that Stacey told him that Miri did not mind her sleeping with Zack. Miri corrects him, clarifying that she did not mind that Stacey merely made the offer to sleep with him. Perceiving this to have been some type of test, Zack admits that during the sex scene they filmed together, they were actually making love and that there was an emotional connection between them, and that he loves Miri. When Miri does not reciprocate, Zack storms out of the coffee shop, quitting the film and his job, and moves out of the apartment.
Three months later, Delaney goes to see Zack, who has moved on to an exterior concessions job at Mellon Arena during Pittsburgh Penguins games. Delaney convinces him to come to Delaney's home to see the unfinished film and help complete it. Zack agrees, and as Delaney and the cameraman Deacon explain, Zack learns that Miri never filmed her sex scene with Lester. Zack goes to Miri's apartment and reveals to her that he never slept with Stacey; instead, they talked about Miri all night. He pours his heart out to Miri, proclaiming his love for her, which she reciprocates.
Zack and Miri marry, and with the help of Delaney and his worker's compensation settlement, start their own video production company, Zack and Miri Make Your Porno, which makes amateur videos for couples.

Question: who told  Miri did not mind her sleeping with Zack?
Answer: Stacey