It seems from the video the child restraint belt buckle released, allowing the Crash Test Dummy to move. We obviously don't know the exact circumstances of this particular test, but clearly the action of the manufacturer in withdrawing the model from sale in AU, suggests there may be a potential issue.
I hope the test authority was competent to carry out the test and had correctly followed the manufactures fitting and use instructions. In which case the video does have very worrying consequences.
Most manufacturers will have designed the child belt system and tested it thoroughly, and will likely employ the same design of buckle across several different models. If my interpretation of failure is correct, the it must raise concerns about other models.
My daughter has two child seats from this manufacturer.