The RTSP protocol itself does not have encryption, for that there is SRTP or proprietary implementations, but it is not common in the streams of the main CCTV providers.
RTSP requires authentication with username and password, but it is not transmitted directly encrypted, if encrypted transport is required it would require the use of a tunnel with SSL encryption for the communication channel.
When accessed via Hikvision or Safire P2P service, a verification code is used to encrypt the video stream transmission communication channel, but it does not affect whether the RTSP port is accessed directly (directly on LAN or remotely via NAT).