I asked my pitching guru (ie my dad) and he said BJ is pitching a two-seam fastball.  He also said most guys don't spread their fingers like that, in fact that most are told to keep their fingers together.  But it's a combo of arm action and grip that makes the ball move.  Every guy develops their own way and what might work for one guy may not work for another. 

Anyway, I once read somewhere that one can tell if a prospect will become a good player if they have a "good face", meaning a strong jaw and determined eyes.  This boy's eyes are electric.