do u guys remember when the 3rd hokage did the sealing jutsu to seal of orochimaru's hand...the 3rd said that this jutsu is used by the 4th. IMO the user of this jutsu will call forth the "devil" sumthing...remember the hand of the devil will pass thru the body of the jutsu user and it will seal it to the user's body(the mark that is on naruto's stomach)...so in order for yondaime to seal the kyuubi the hand will oso pass thru his body and be sealed into himself.....tat time wat happen i really dont know....maybe yondaime turn himself to a baby or maybe the side effects of the jutsu itself