I don't remember where I got that, so I'll do some google research.
https://www.investopedia.com/articles/markets/050614/introduction-dark-pools.asp
Quote:
there is no order book visible to the public. Trade execution details are only released to the consolidated tape after a delay.
https://www.investopedia.com/terms/c/consolidatedtape.asp
Maybe what Brew is talking about is a service that lets you see those details before the consolidated tape is completed