I am totally believing that Sony is behind all this GT5 leakage to keep everyone on their toes. It might not have been intentional, as some employees might have ran off with GT5 copies illegally. But Sony would've been able to track these thieves rather quickly. Simply look at the missing batch number and figure out which time slot the employee could have ran off with the game, then go take a good look at security cameras and Bam, there goes your suspect. Another way to track them down is through PSN. The guy was online when he filmed Cape Ring, so it's not difficult to track the people who played GT5 and figure out IP address and such.
In most likely cases, Sony already got hold of them and probably struck a deal to let them keep their copies, but must keep their lips shut and can only upload videos that are pre-approved by Sony. Otherwise, they will be looking at a fat lawsuit and possible jail time.
On a side note, I'm going to make an educated guess that Sony won't announce GT5's release date until after NFS: HP and Assassin's Creed comes out, even if the date is one week away from announcement.
