DW just bought one of those Ring camera/doorbells from Costco. Works pretty good and doesn't cost much. She's an iphone addict and it's yet another thing that she can play with on it. :( At first it was going off multiple times a day until we figured out it was birds flying around the front porch. Must be a nest up on the roof somewhere. Dialed back the sensitivity a bit and is now fine. Video images get stored in the cloud and I think for up to 6 months.
When I built our house I hardwired to a sensor on every door and window, motion sensors throughout and a few glass break sensors. It's alarmed like Fort Knox and monitored 24/7. I also ran wiring to 10+ locations around the house for cameras but never installed a video surveillance system which wouldn't have sent a notice by phone anyway. Another part of our alarm system is my SIL who lives in a suite above the garage - she's actually paying us to be part of the monitoring system, lol!
We're in the country with neighbors several hundred feet away and having a camera as well is nice so we can see if unwanted people come down the driveway. The Ring picked up a couple of JWs this past week so it does work! :) Lots of similar ones on the market these days.
Went to a local home show the other day and ADT had their system including video monitoring on display that they were hawking. OMG, what a terrible pitch from the sales girl, technically and money-wise. VERY expensive. She scribbled a lot of notes (mostly illegible) on a large piece of paper and wouldn't even let us keep it afterwards. What a joke. Wouldn't have bought from them anyway but just wanted to hear what they had.