Two-thirds of the crew, 841 men, lost their lives; but probably not from the explosion. Those who died were either killed by the torpedoes or trapped below decks. The survivors had already abandoned ship when the explosion - probably resulting from cold water entering the boilers - took place.
http://www.hmsbarham.com/
Also, that first clip is at least four years old, as that's the first time it, or one like it, was posted here. And it's a modern torpedo going off well under the keel of a lightweight modern frigate. There are plenty of clips from the Second World War showing torpedoes hitting ships, and they look nothing like that.