Activity Zones allows you to mask off certain regions to prevent excessive motion clips or false alerts. This feature is great if your cameras are outside and you have a tree or bush blowing in the wind triggering a motion clip.
To use this feature, open up the settings on the camera that you'd like to modify.
Once in your camera's settings, tap where you see Activity Zones (Beta)
When you're in Activity Zones, you'll see your camera's thumbnail with a grid pattern overlaid. If you've moved your camera recently and haven't updated it's thumbnail, go back to the home screen and tap the thumbnail icon.
On this screen, tap the squares that you DON'T want to record motion clips. In this example, we'll be disabling the areas that have bushes, since they can blow in the wind and cause us false alerts. Any section that is grayed out will not record a motion clip.
Once you're happy with the zones that you've disabled, go ahead and tap Done.
You'll be brought back to the Settings screen, and you'll see that the settings were applied, as the grid pattern will match what you just set.