I enjoyed this article and find the service this company offers intriguing. I've watched a bunch of videos and see a lot of value in paying for a very professional interview with actual feedback, something that is immensely difficult to get from "real" tech interviews.

There's one thing that concerns me, it's the line: "We make money in two ways: engineers pay us for mock interviews, and employers pay us for access to the best performers."

I definitely don't want to equate this with the legal but perhaps disreputable "pay-to-play" or "double-dipping" practices of charging both job seekers and the companies trying to hire them. This looks like a good company, and it makes sense to offer a paid service for people who want to practice but aren't looking for a recruiter. Still... I see a potentially uncomfortable situation where someone who wants a job is paying $150/hr or more to take a mock interview for a recruiter who would then market the candidates who are able to pass.