It's Calif. They're named in the post.

>As a result of the leak and pre-announcement around 20:00 UTC, Calif, one of the security firms that had reported the issues mistakenly published a video. It showed their proof of concept working against a number of targets and revealed a few additional, though limited, details about the vulnerabilities.

You can see the same demo video on their site: https://calif.io/php2shell/#php-5-4-0-rce

calif.io