They are wired using a usb cable.
They can detect motion from behind glass.
I don't know how much data they use. They only upload a few seconds of video to the cloud when motion is detected. Obviously if you are viewing the camera via the app you will also use up data.
Get a memory card from MemoryC.ie
Yi also do more expensive outdoor cameras if you need those.
I considered using a similar setup to what you describe.
Indoor, wired.
First thing is, I can typically easily find 1 m USB cables, but cables longer than 1 m?
I assume you're using lengthier cables?
Where did you pick them up.
And secondly, in your experience using them they can pick up motion even from behind glass, provided you disable the IR sensors?
Does using the cloud require a subscription?
.......
And for me, I'm running wifi from a phone hotspot, which means it would be preferable not using a phone app to access the video-feed (as normally the app runs on a phone separate to the hotspot phone).
I know Eufy and Ring do online access to camera footage (instead of having to download a phone app, one can simply log on to their website to access recordings, live feed etc).
Any idea if Yi supports this also, or do you access your camera info exclusively through a mobile app?