The first part was normal but then it took an unexpected turn.
Her dog started digging a hole at the beach, as she recorded him. Then, he became intensely curious about something in the hole, and stuck his snout all the way in.
Soon enough, a crab popped out, snapping at the dog and trying to protect itself. Then things calm down, as the animals get to know each other. In the end, they seem to have become familiar enough with each other to stop fighting.
Oliver Markert, who recorded the video, says that his dog Sheila enjoys digging out crabs and playing with them.