That message is traced when the AVCastManager.destroy method is called. This method can be called by the developer OR it is called internally by the AVCastManager itself when the user gets disconnected. I suspect that after 5 minutes of being idle, the user in your application is disconnected.
Please notice that the user is considered idle when no messages are sent from the client to SmartFoxServer. As the a/v connection is between the client and Red5, this is not taken into account. You should probably implement a sort of ping to SFS to avoid being disconnected.
