Microsoft appear to be introducing "Cast To". In a very clunky way. E.g. right click on a folder on Desktop Win10 and you have a Cast To menu option. But no such menu appears to Groove. In the Videos app when playing a video there is a Cast To button. So all a bit flaky.
Suspect this was something unable to be finished by this first release.
Not sure what device you used to Play To, but Cast To looks focused on Miracast currently.