Cloud stored with 3 hour loop of storage, the $9/month increases the loop timer to the 30 days (this timer also depends on your model as some get a better storage limit than others). I would be thinking the Cloud Storage is Google’s Cloud (I don’t see them hosting it other than on their system or contracted storage systems). For a short period when the internet connection is down the device will store some length of video but once reconnected to the web it uploads the stored video to the Cloud service. There are two systems for storing the data, one is the Nest Cloud storage and if you link your Google account the data is stored with your Google account storage. Neither of those two systems fills me with any confidence about what will be shared through the Googleverse. I add though that Amazon etc are just the same when it comes to what they need they will use.
How Nest cameras store recorded video - Google Nest Help
As to the privacy of that data…forget it
FAQs on privacy: Google Nest - Android - Google Nest Help
Ring devices
How to Save Ring Doorbell Events to Local Drive – The Security Camera Guy
If you have the Free plan no storage, you have to pay to get storage starting at the Basic plan
Protect Plans | Home Alarm Security Monitoring Service | Ring
From a July 2021 review on TomsguideDOTcom ( Best security camera storage plans compared: Nest, Ring and Arlo | Tom’s Guide (tomsguide.com)) These figures are US dollar rates not Aus dollar ones, and the review may be worth a read for anyone considering what to get (if anything).
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Free plans
If you don’t sign up for a subscription plan, most cameras are limited not only in how much video footage you can view but also in what features are enabled. Here’s a summary of the features available in each company’s subscription plan (and a source for more details on each product).
Arlo: View live stream and receive notifications.
Blink: Live view streaming
Canary: One-day history, video clips, custom activity zones, person detection, for up to four cameras.
Nest: 3-hour history, people, animal, vehicle, and package detection, and custom activity zones.
Ring: View live video and receive notifications.
Wyze: 14-day rolling cloud storage (up to 12-second clips), custom activity zones, 2-way audio, smoke & CO2 alarm detection.
If you want to go the free route, both Blink and Wyze have free storage, as well as a number of other features that are only available via subscription with other security cameras.
Paid subscription features
When you step up to paid plans, each company offers extra features in addition to cloud recordings. We’ll get to the pricing in a moment, but here are the features that are enabled once you subscribe to a plan.
Arlo: 2K and 4K video; downloadable 30-day video history; Person/vehicle/animal detection; package detection; customizable activity zones, emergency response service
Blink: 60 days rolling video storage, optional local storage.
Canary: Unlimited video downloads; desktop streaming; two-way talk; custom arming modes
Nest: Continuous recording; Person detection; Facial recognition
Ring: Save and share live video.
Wyze: Complete motion capture. Will record the entire motion event, rather than just a 12-second clip.
Arlo users can also subscribe to a CVR (continuous video recording) Plan, which will continuously record video to the cloud. However, you can only view this video, not download it. A 14-day CVR plan costs $10/$100 per camera, and a 30-day CVR plan costs $20/$200 per camera. The price plan for each additional camera is 50 percent less."