A:Answer My six ARLO Pro-2 camera-system includes a Base Station with two USB ports and on one of them I'm using with a USB memory stick, as a storage device of alerted Camera-Videos. With an I-Phone's Arlo app, one can also get alerts with videos, saved to the phone.
I have not found a need for any additional back-up DVR or WDR devices, but I did find, that the cameras SHOULD be hardwired, to better utilize all the features the camera system offers.