Toddler confused about mirror's reflection: Hey, where did that baby go?

When my daughter was little, I had a mirror leaning against the wall for her to look in. For a while, she thought she had a playmate and would interact with this "other" baby. She would laugh with it and sometimes even kiss it. It was adorable. So I had to chuckle when I saw this video. This little guy probably hasn't had a mirror at his height before. From what I can gather, he thinks this standalone department store mirror is a window and that if he could just get around it, he could play with his new friend.