Try the free version of NX-V first and check your cameras or NVRs work with the app.
Not recommend for use on iPhone less than 8 or on iPhone SE (1st edition) - the app will work but the screens are too small to benefit from all the features.

NX-V PRO adds advanced features to the free version of the app.

• Supports viewing NVRs and multi-channel cameras as individual cameras or in multi-camera view.
• Human Body detection with pre-event video recording (iPad only)
• Motion detection with pre-event video recording
• Configurable pre and post event recording
• Access to remotely stored videos on FTP servers
• Access to onboard recording and event history
• Set your camera's GPS location and view a map of all your cameras.
• User management - add/remove and edit camera users.
• System features, view log and reboot camera
• Sync camera settings, locations and groups between your, iPhones/iPads or NX-V PRO on your Mac

Notes: 
Not all cameras support system admin or onboard storage and the available functionality varies by camera. 

The ability for the software to playback videos from onboard storage at the exact start time depends on how the firmware in the camera/NVR behaves.

If your camera or NVR provides individual replay URIs for each recording event the app will be able to play this back and capture the video stream to save to a local MP4 file.

On some devices no timing information is provided by the firmware making it impossible to move to the exact start time of the video.

NX-V is also available for iOS and Apple TV