Correct that you do not get recordings without the subscription. I also have not purchased a subscription and I agree it isn’t necessary (for me). However, you will get live video on demand in the Ecobee App or on the Apple Home app. Also, when the doorbell is pressed, you can see the video on the thermostat screen and it also pops up in the corner of yout TV if you have an Apple TV.No hub. A sub is only required if you want recordings. Otherwise you get snapshots of motion activity only. And it works great with HomeKit. Just not HomeKit Secure Video.
Speaking of which, I’ve recently lost the ability to see the video on my thermostat following a doorbell press. Now I usually get s spinning icon, and sometimes the thermostat reboots. I’m not sure what the problem is. I can select the doorbell from the thermostat and see live video. I should give Ecobee a call.