It's 'clever' play from Marcus Browne. Running on to a through ball (which he hasn't yet touched or got under control), he doesn't run at an angle to try and put the ball towards the goal, but to keep himself between the ball and the goalkeeper. At the last moment, he flicks the ball (away from goal and out of play) and makes sure he runs into the keeper, who is chasing out. So technically it's a penalty, and the keeper should have been more careful, but I can see why a ref is reluctant to give it. Giving a corner is baffling though, and an indication of bottling the real decision. And he got both other penalty calls wrong too.