A playlist interface is provided for display on a user device, the playlist interface comprising a selectable indicator located after a first media item in a playlist, the selectable indicator presented in the playlist interface after the first media item to indicate that, upon selection, a second media item is to be added after the first media item in the playlist, wherein the second media item is an interstitial. Upon a user selection of the selectable indicator located after the first media item in the playlist interface, a plurality of user interface (UI) elements are caused to be presented to allow a user of the user device to specify configuration parameters for the interstitial being added to the playlist. User input is received for at least a subset of the plurality of UI elements to specify the configuration parameters for the interstitial. The interstitial is created based on the received configuration parameters, wherein the created interstitial is supplemental content to be added before or after one of a plurality of files of a plurality of media items of the playlist.