Yeah, Mine is hooked up to a small Linux PC that does all of the streaming stuff. Plus, I don't have to worry about an app being supported and I have a wireless keyboard as well. I had a IR dongle for using with a remote but the keyboard is easier to deal with.

Ethernet can be carried across HDMI. It wouldn't surprise me if some try to connect this way, even if they don't tell you it's doing it.

I ended up with an off-brand smart TV and connected it via the Ethernet plug with an inline switch I keep off most of the time (and I never gave it any Wi-Fi passwords, though of course Google could easily use its password database to bypass that). It could run fine without ever being allowed to connect to the Internet. The only app I use is SmartTube Next, which could easily be done via a streaming device connected, which is the right way to do things as the article suggests. For one, you don't risk bricking the OS with the constant updates the smart TV downloads. I'd rather brick a streaming box than the whole TV.

There's no way to know whether it captures HDMI input periodically, saves locally, then uploads when connected to the Internet.