It is not yet known how the footage was obtained and it is not the first time it has been loaded on to the internet - a leaked copy was also discovered in 2004.
Police have launched an investigation to determine how the video was stolen for a second time.
Brisbane-based trauma psychologist Paul Stevenson, who worked for many years with massacre survivors and victims' families, was dismayed the video had resurfaced.
"To post this is a nasty, terrible thing to have occurred," he said.
"Watching or hearing it is a re-experience, all of those things people felt at the time come back. The tragedy occurs all over again. This is a real worry for families of victims."
Bryant is in the psychiatric wing of Risdon Prison in Hobart, Tasmania. The sentencing judge ordered he remain in prison for the rest of his life.
- NZPA
