To continue watching videos via YouTube application after leaving its main menu, you had to be one of the subscribers of YouTube Premium. At an additional cost, users of this subscription receive access to some of the additional functions, and one of the offered options is Picture-in-Picture mode, thanks to which we can watch the video in a smaller window while performing other activities on the smartphone. YouTube has decided to change slightly company's policy, as it looks that the Picture-in-Picture mode will be gradually made available to all users at no additional charge.

This feature has been available for free from US users for over a dozen months, but in the last few hours more and more users from other countries (for example from Italy) began to report that they received new option in the settings. To use the Picture-in-Picture mode, you must enable it in the application's settings on the phone, because in default it is disabled on all smartphones.

source