I recall watching confessions from a tech boss who used the interview process to get coding answers his own staff couldn't figure out. He'd post a job position for a much higher level than he had in-house, interview several candidates to get their answers, but hire none of them. He'd only have to do it once in a while and it was far cheaper than subbing the job out.
He wasn't alone in doing that.
Can you please supply a link to that video, or what YouTube “channel” to search for it?