I like the implementation, but if folks didn't like the NSA spying on them, they might not like this. This is wiretapping on steroids. I'm assuming the interviewer watches every keystroke. Creepy. I'm sure authors, well spoken and in full command of the English language, would get annoyed at someone staring at them to see if they can write a novel.
Tech interviewing is broken, but all solutions historically point to trying to watch a person code. I don't think that's the solution. When folks realistically work on multiple tech stacks with multiple frameworks and multiple languages, what is to be gained by zeroing in (deeply) on only one aspect of it.
This explains the need for a tech interview "study guide" posted earlier in the day. You're working on stuff contextually needed for your current job, but you'll be tested on stuff you don't use daily/monthly/yearly? That's insane.