Meta's Mark Zuckerberg and Adam Mosseri are betting on long-form. Kevin Mazur/MG26/Getty Images for The Met Museum/Vogue

Instagram's top executive, Adam Mosseri , has a plan to keep the platform "culturally relevant" — by making it more like YouTube.

Meta-owned Instagram unveiled an overhaul of long-form video features on Monday, including a test of horizontal videos called "Features." Taken together, the changes make the app feel a lot more like YouTube.

"We want to be the most culturally relevant platform," Mosseri said in an interview with content creators and founders of Press Publish, Colin Rosenblum and Samir Chaudry. "To do that, we just need to show up where people are."

The context: YouTube has become a major hit on TV screens, and there's a growing appetite for Instagram-native shows with recurring episodes.

"Subway Takes," hosted by Kareem Rahma , is a prime example of Instagram's strengths and limits.…