Charles H. Lightoller was the highest ranking officer to survive the sinking. His stories and testimony were given considerable weight at the subsequent hearings (at the Waldorf-Astoria Hotel). Here is his harrowing account of the sinking. Some of his recollections are inconsistent with the simulated sinking as noted.
I stuck to the ship until the water came up to my ankles. There had been no lamentations, no demonstrations either from the men passengers as they saw the last life-boat go, and there was no wailing or crying, no outburst from the men who lined the ship's rail as the Titanic disappeared from sight.
The men stood quietly as if they were in church. They knew that they were in the sight of God; that in a moment judgment would be passed upon them. Finally, the ship took a dive, reeling for a moment, then plunging.  I was sucked to the side of the ship against the grating over the blower for the exhaust. There was an explosion. It blew me to the surface again, only to be sucked back again by the water rushing into the ship.
This time I landed against the grating over the pipes, which furnish a draught for the funnels, and stuck there. There was another explosion, and I came to the surface. The ship seemed to be heaving tremendous sighs as she went down. I found myself not many feet from the ship, but on the other side of it. The ship had turned around while I was under the water. 
I came up near a collapsible life-boat and grabbed it. Many men were in the water near me. They had jumped at the last minute. A funnel fell within four inches of me and killed one of the swimmers.  Thirty clung to the capsized boat, and a life-boat, with forty survivors in it already, finally took them off. 
George D. Widener and Harry Elkins Widener were among those who jumped at the last minute. So did Robert Williams Daniel. The three of them went down together. Daniel struck out, lashing the water with his arms until he had made a point far distant from the sinking monster of the sea. Later he was picked up by one of the passing life-boats.
The Wideners were not seen again, nor was John B. Thayer, who went down on the boat. 'Jack' Thayer, who was literally thrown off the Titanic by an explosion, after he had refused to leave the men to go with his mother, floated around on a raft for an hour before he was picked up.Here is a video link to a slightly different take on the mechanics of the sinking: link
 Lightoller testified that she did not break in two. This contradicts fact and it's difficult to reconcile his testimony. One reason, perhaps, is that Lightoller saw Jack Thayer's depiction of the breakup and decided it wasn't what he saw. Thayer's description, depicted here, shows the bow section magically refloating after being submerged. The chaos of the sinking led to a Roshomon effect.
 As the ship sank, many air vents become inlets for water. A suction effect could have trapped him against a vent grating. Occasionally, trapped air would have to escape, sometimes violently. Also, though the boiler fires were raked down, they were not extinguished. Cold seawater would have produced pockets of steam.
 Underwater gyrations from breaking in two could have caused this.
 This seems to have happened much earlier in the simulation video than Lightoller's description. The other stacks are shown to remain in place until she submerged.
 The men actually stood on the capsized boat for several hours until they were picked up.