Stolen web cam footage
Webcams are known for their low manufacturing cost and their high flexibility, making them the lowest-cost form of videotelephony.
As webcams evolved simultaneously with display technologies, USB interface speeds and broadband internet speeds, the resolution went up from gradually 320×240, to 640×480, and some even offering 1280×720 (aka 720p) or 1920×1080 (aka 1080p) resolution.
Many newer devices can produce video in multi-megapixel resolutions, and a few can run at high frame rates such as the Play Station Eye, which can produce 320×240 video at 120 frames per second.
You can get a system that costs just as much as a Nest Cam but comes with a handful of cameras that you can place around the house in various locations.