I found motion detection in general to be waste of time for false alarms (wind, clouds, bugs, etc...). My china brand cams have no gateway access anyway so no value even if motion were reliable.
Defining just what that "something" means varies for everyone.
For instance:
I'm remote on acreage and mostly home so biggest concern is vehicle traffic coming/going when I'm home and away. I use a 100% reliable magnetometer buried along side driveway that triggers camera's to email pic and time stamp which make for easy searching of recordings.