The free diver was on his way back in when he must have seen the whales and quickly got out onto the rocks. It seemed like there was at least 4 Orcas around him of which one was a mother with her calf.
The one Orca came very close to shore where the Labrador was busy retrieving sticks from the water. He saw the whale and quickly turned around and swam back to shore with the Orca following as far as he could go
Orcas have never been known to attack humans in the wild, but that doesn't mean they can't scare a person who happens to be swimming in their domain. The accompanying soundless video, shot in New Zealand, shows a spear fisherman being frightened from a small bay, while a much braver dog (watch from the 42-second mark) swims with the orcas briefly until finally being pursued to shore by a large orca.
This occurred in Matheson Bay near the Auckland community of Leigh. Viewers can also see a man and a child coming to watch the orcas, which are practically within arm's reach, from the rocky shore. The dog, once it emerges from the water, can be seen barking and seems to want to go back in, but chooses to stay ashore.