Digital Video Recorders (DVRs) are usually machines that take a video stream directly from the camera through a connection in the back and store that video stream on a disk, while Network Video Recorders bring the video stream from the network. So, for the AyrScout Cameras, you need an NVR.
If you are using the cameras for any type of security (i.e. not just as an "extra eye" you check once in a while), we recommend using Vitamin D or Blue Iris on a PC that's on 24x7. Of the two, Vitamin D is easier to set up and has better motion detection features, and it runs on both Windows and OSX. Both of them are free to download and evaluate.