She's the right field foul line ball girl. You can see her come into the screen on the right. He, avoids a tackle by hurdling a would-be tackler, heads in her direction followed by four security guards. He makes a move like he's going to her right but stutter steps and cuts it back left. She, like a classic tackler, is moving laterally and moving her feet so that her hips don't get turned. He thinks he's by her and is surprised by how hard she pushes him as she lays out to her left and goes to the ground to make sure she stops him. Classic play of the day that would make her father proud.