Nest Secure and Nest Hello/Nest Cams are not integrated in this way, there is no way to even configure Secure to alarm based on what a Nest Hello/Nest Cam sees. The only things that trigger Nest Secure alarms are opening, motion or tampering events on the Detect door/window sensors.
In the Nest app check the Security History on the Guard, see what actually triggers your alarms there. You might have a sensor getting triggered by something like curtains or a plant swaying when your HVAC runs, being too near to a heat source etc. See which one is causing it and try moving it elsewhere.
I am relieved to hear that your issue has been resolved! At this time, I'll go ahead and lock this thread. If you're still experiencing problems, feel free to start a new thread and we'll be happy to help.