How did my girl learn to associate things with A - Z

She learned this from various sources, without my supervision. I was surprised when she told me, as I didn't teach her this. She likes the song of ABC, so she'll request me to search for this song from youtube for her, and I'll normally searched songs with title "ABC" and pass her the Iphone to let her choose the song she wants. From the list she found other ABC related songs and clips, one of the good ones are this which teaches A-Z phonics and things associated with it:
Youtube Phonics Song
So she learned this A is for "Apple, A, A, Apple...." and etc. She also learned from those block books and picture books given by my sister in law. So do not under estimate the ability of the children, they can self-learn pretty fast.
In the clips above, she didn't say out the full list of A - Z, and she started to talk nonsense when comes to H, is very difficult to video tape her as she doesn't have the patient. But I managed to record it as a voice clip when she was about to sleep one of the nights:
Click Here to hear the voice clip :)