I'm not so sure it shows his death, as such - just him losing consciousness. I know that's splitting hairs, because we know now that he died a little later.
From what I've read in all the stories, the tape ends when he passes out. Others reported that he was still alive when taken to the boat 2 minutes later, but never regained consciousness.
" ... Irwin's manager and producer John Stainton described the footage, which he had seen, as "shocking."
"It shows that Steve came over the top of the ray and the tail came up, and spiked him here (in the chest), and he pulled it out and the next minute he's gone," Stainton told reporters in the city of Cairns where Irwin's body was taken for an autopsy.
"That was it. The cameraman had to shut down," Stainton added. ..."