he said itachi was 11 when he met up with madara/tobi which I think he was almost right but I think Itachi was 12...I put it up on the last one but I guess i'll do it here too...
"Itachi Uchiha apparently joined Akatsuki before carrying out the Uchiha clan massacre for which he defected from Konohagakure, though his membership seems to have come with the stipulation that Akatsuki could make no direct movements against Konoha. When Itachi joined, Orochimaru attempted to steal his body in order to gain the Sharingan. This failed and he was forced to defect."
"Eight years after the Nine-Tails' attack, Tobi infiltrated Konoha to try to rekindle the flames of war. He was found by Itachi Uchiha first, who convinced Tobi to spare the village in exchange for helping to wipe out the Uchiha clan for deserting him decades earlier. Tobi complied, training Itachi and providing assistance."
this means that itachi had to be like 4 when the nine-tails attacked because 4+8=12. so itachi was 12 when he joined akatsuki which gave tobi time to train him before they took off to kill his clan. if he was 13 already it would have only left them a few weeks or days to train. so he was 13 when he became anbu captin but you still have to remember he was already in anbu at the age of 10. so I think at the age of 12 Itachi had to spy on his clan while doing so he got the mission to kill them. he tried to find a way for the 3rd to change his mind but couldn't. so not having any other option he found madara, joined akatsuki and began to train. when he turned 13 he became captin and as soon as he did he took out his clan and left the leaf
if you add up the years it works
for Itachi:
4 (years old)+8 (years after the fox attack)=12(his age then)
13(how old he was when he killed his clan) + 4(when he met back up with sasuke)=17 (itachi's age in part 1)
for sasuke:
17(itachi in part 1)-13(sasuke in part 1)= 4(how many years older itachi is)
13(when itachi killed his can) -4(how many years older itachi is)= 9(how old sasuke had to be when his clan died)
9(sasuke younger) + 4(when they met back up)= 13(sasukes age in part 1)