but are they static connection terminals that are screwed fast (can't see the back) or a flat strip of copper that bites down when pulled taut?
There are no screws. Just push the wire in and it holds it in place. I use wire nuts but I bought a small package of those connectors just to look at them. They do appear to be stronger than the failure-prone push-in holes on backs of devices. I keep those connectors with me for those situations when there is a short wire in the back of a box where there is no room to put on a wire nut.
They seem like a great idea, but are they a novel idea?
Contractors are starting to use them since its quicker, and there will be no immediate call backs for non-working circuits (like there is when a wire slips out from under a wire nut). They don't care if they fail years from now. But from what I hear they are promising.