The Swann system uses older AHD video feed tech. Basically analog video signal down a coax cable, plus an additional twin 12v power feed.
There are newer systems which are IP based, where everything is on one cable. Power over ethernet (POE). Easier to install, easier to integrate into the network- and best of all, the recording device or digital video recorder (DVR) can be in a remote location for extra security.
Access to the video content is as secure as your network.
I've got both systems at home and I personally think IP based CCTV is the way to go. Plus if you're technical, you can build your own system up from scratch quite easily. Just make sure you change all the default passwords once installed!
A 4TByte HDD with 4x 1080P cameras recording at about 4 frames per second provides a month's worth. The higher the recording rate, the more memory you need.
Search for 1080P IP camera. The best ones are based on Sony camera chips. Usually IMX323 or IMX291 image sensors, although higher quality, higher resolution seems to be the way it's going...