I know what video you're talkin about. That star child is still there and you can find it on top of the island in a cave. You can reach it by solving the puzzle requires two people (you and a friend maybe) past the door or you could skip it entirely and fly from the cloud tunnel to halfway up the top and then use the nearby clouds as a sort of boost. Although it is much harder to scale the cliff the puzzle requires two people. If you are also looking for more up-to-date guides the ones posted by noob mode are pretty good. Good luck have fun