Fake plates. The bar would have at least some bend in it on movements that fast. Plus no one benches big weight or weight close to their max as fast as he did.
Those for sure are fake weights. Check out his body language (lower body neck etc) and watch him rack 315. That shit would put some serious strain on even the most powerful bench pressers. Also look at the light bulbs flash, these guys are serious millionaires who would only put this shit out there to look good. Plus Shaq has already stated that the weights are fake