Russian representative at UN SC two days before that mentioned in his statement that Ukrainian military forced inhabitants out of a different maternity ward in Mariupol and made fire points there. [0]
Now look at the woman at 1:10 in your video. Here is a BBC's interview with her[1]:
"But Marianna told me there were no Ukrainian military stationed in the building where she was. She says she saw Ukrainian soldiers in the oncology unit in the building opposite the maternity unit."
My take is that at worst it was a strike made by mistake by people who were unaware that the hospital wasn't evacuated.