Greg - 10/23/2012 3:23 PM 
Here is my take on the video update:
According to other divers that knew him, the instructor/cave diver that died as a result of this accident had a reputation for pushing the limits. It’s possible he could have filled the tank beyond it’s safe operating pressure.
His scrub bottle was filled with high concentration of oxygen, not sure what percentage.
The tank did not fail spontaneously, something ignited the gas in the tank, right near the valve. He could have dropped the tank.