Trouble is idiot on pursued bike doesn't have any regard for other road users, damage or injury they may cause. The cop even on a more powerful bike has to keep up whilst taking all of these things into consideration so the fact the target vehicle seemed at times to be getting away is no reflection on their skill as a rider. That said, maybe knowing what would happen to them when the Brazilian police caught them may have made it worth risking life & limb to get away.
Wouldn't happen in the risk averse, PC UK anyway as the cop would have been told to stop the pursuit as soon as it started.