Probably lost connection before the camera finished recording the video. I had it happened when I shredded the Deuce98. This rocket has glassed plywood fins.
Probably lost a fin. That's why it took the 90 deg turn. Seen it happen many times and with a cardboard rocket, the damage to the rest of the rocket occurs from aerodynamic forces. I've been flying cardboard rockets for over 30 years and still do. You can use a motor 1/2 the size as a fiberglass rocket the same size. With the introduction of dual deploy in 1995, I was able to double the motor size (and altitude) for the same amount of walking