The encryption feature is used for encrypting a device's videos (including live videos and recorded video files) and captured pictures. After you enable Video and Image Encryption for a device, you can set a password, so that the password will be required when someone tries to view videos and images of the device for the first time.
If you log in to the Mobile Client with the same account on another phone, you should enter the device encryption password again to view the live videos, the recorded videos, and pictures from events.