Add heartbeat detection to verify the person is alive. [1] has one example, Google "use webcam to detect heartbeat" to find more.

[1] https://github.com/thearn/webcam-pulse-detector

Measurement of other minute facial feature movements besides blinking to detect whether it's a real person vs picture or other video?

I think we've just discovered the real use for Apple's Face ID. Staring contest video games.