The one of the Discovery Channel. They figured the wire in the fuel probe touched another wire in the same harness that was outside of the fuel tank. They examined other aircraft still in service and found numerous aircraft with chaffed wiring.
They recreated the explosion I believe at least twice. They also placed a structual part of the aircraft they felt had failed and initiated the break up behind the cockpit. This part failed in the test.
Ahhh, the Discovery Channel, home of the Myth Busters! Wonder if the fearsome duo also produced this Wonderful Documentary?