The videos came from hundreds of Italians across the country as they observed a nationwide lockdown, but the message for other countries was the same: Don't underestimate this.
Parenti asked them to record themselves and share what they wished they would have told themselves 10 days ago, knowing what they know now.
"Yes, 'cause infections in Italy will continue to increase, proving [to] you this all wasn't bulls--- like you thought," another said.
"Up until nine, 10 days ago, we were behaving the same way," said Parenti, who lives in Milan. "We were going outside saying, 'It's just a flu. We get it ... why should we worry?' But the thing is, we didn't realize how little we know."
"We make assumptions that not only put us in danger, but others in danger," Parenti said.
Working with the film collective "A Thing By," Parenti received hundreds of videos for the project. He said he edited the whole thing in one night to get the message out as quickly as possible.
"What is happening is much worse than you thought it was," a woman named Paola Costa said in her message. "You'll realize that even just being able to breathe air in your own house, it's something you should already be grateful for."
A woman who works at a hospital in Italy said she's now working "deadly shifts."
"We took it lightly," she added.
"Maybe rethink your Saturday night plans," another man told his former self. "And who knows? Maybe had you stayed home I wouldn't have to be home now."
Parenti hopes the sobering warnings will be a wake-up call.
"It's almost become cool to be a skeptic of things, but there's nothing cool about taking risks at this time," he said. "We have so little to gain from risking it, but we have so much to lose by not being patient, not being prudent."
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ABC News' Alice Chambers contributed to this report.