The existing cable will most likely be 230v, most if not all DIY camera's will have a dedicated power supply inside the premises and require a low voltage (often 12v dc) cable running to the camera.
So no, in most cases your existing cabling would be no good.
The one in the Amazon link is quite deceiving (often on purpose) as it has a few photo's that would lead you to believe the camera is totally wireless, when it needs a cat 5 cable all the way back to your router.