For some reason, for the initial phone interview they made the creepy demand to do a video chat even though I was only 30 miles away.
The interview question was a programming puzzle, even though everyone knows that puzzles don't prove anything and are useless as interview questions. However it was doable and I solved it... once they finally explained it. It took some time for them to reveal all of the details and it seemed very much like they did not know their own question, nor how to solve it. They frequently interrupted me, making it difficult to concentrate and do the task. After I solved the puzzle, they seemed offended that I had done so.
The overall impression was that the interview was more of a fraternity hazing than a real interview. It clearly wasn't intended to assess skills or gauge intelligence. At best it served only to boost their egos.
When I asked them how their product compared to their main competitor Optimizely, one of them answered saying literally said he had not tried Optimizely.