Good documentary, really spelled out the time-line of how/when delamination of the carbon fiber hull occurred. A great material in the air, but the nature of pressures exerted are exactly why it shouldn't have been attempted in the first place. But hubris wins more times than not, unfortunately.
The loud plinking was horrifying. Like the one guy said, why send it down with people in it when it was being tested???
Rush had to know it was the sound of delamination of the fibers. With his reputation and $$ on the line, he was likely riding on the hopes it could withstand a few more dives. All the acoustic monitoring wasn't going to dissuade him. It was an inherently flawed design that shouldn't have been built.