The timing of release is really crucial on it and yeah you just need to press X for a tip-in (or what ever shot button you aligned) just like if you on the way to the board to catch a rebound as it already described in the tutorial you mentioned.but in my concerns its one of the more if not the most difficult plays ingame cause its the less repeatable of them all so its hard to really workout on it cause of the little time window you have executing it and all the different jump angles and ball bouncing of the rim you about to have.so if you to early you just jump into thin air if you to late you just jump into thin air, if you come from bad angle you just jump in to thin air, you wont do it too if someone in front of you is boxing you out or if he just catches the rebound while you might finally got the timing right and you in the final animation already, so just like in real life its a hard play to do and a lot of things need to go right, even need to consider if the backcourt stabil or not to attempt it.
X = shot button / tip-in = x-button / putback dunk = sprint button+x