"Airbnb's policy on cameras says that they can have a [doorbell camera], but they cannot have anything inside the property," Walsh said in a second TikTok video.
"It's the same as like staying in a hotel. You have an expectation of privacy".
Walsh didn't believe the host planted the camera but speculated it could be someone who had regular access to the apartment.
"I don't think it was a guest unless they left it there," she said. "But it had to have been someone that was there all the time because it only recorded to the SD card".
Airbnb refunded her stay but Walsh did not say what the police investigation concluded.
Similar cameras online tend to cost upwards of $30.
People 'not surprised' by her experience
The original video has been viewed more than 7 million times and hundreds of users commented saying Walsh's experience is their "biggest fear".
"I literally changed my clothes in a dark Airbnb closet the one time I stayed in one cause of this," one viewer commented.
Others offered ways to identify the camera's owner.
"Put the micro SD card in a computer. The first video should be the person who originally plugged it in," one user wrote.
Despite the unnerving experience, Walsh said she will continue to stay at Airbnbs.
"There also were a lot of people who were [saying] 'that's why I don't stay at Airbnb', but honestly, the chances of you encountering the situation with or without your knowledge is much higher in a public bathroom, or like a dressing room or even a hotel," she said.
"So I think that's dumb. I will definitely stay at Airbnb again".