Once picture-in-picture is toggled on in both the YouTube app and system settings, users can reportedly just navigate away while a video is playing and it will automatically minimize toa corner. The feature doesn't work with most music videos, according to the service's FAQ page. It's unclear how long it will take to roll out to all Android users, or when it will extend to iOS. But given how YouTube is starting to add the feature for desktop users (albeit without keeping the window when navigating away from the page), this could mean it's coming to non-Premium viewers across the service.