I wouldn't think a Herc fuselage could be fatally damaged by a thrown prop blade. The fuselage is pretty tough (as evidenced by the fact this one is still recognizably an airframe, and not aluminum confetti, after a 20,000-foot fall), designed to take combat fire and survive, and thrown blades have passed through the cabins of "lesser" turboprops (e.g. DHC-8-xxx, ATR) without causing those planes to fall apart.
Of course, if a thrown blade hit something
else, inside, (LOX, pyrotechnics), that would be a different story.
On the video footage there is no apparent sign of the fin - quite a large structure on a Herc.
I noticed that also. But that could either be the primary event, or just a result of, say, the "flat spin" patrickal mentions.