But I think it was accidental, I've just rewatched this clip a handful of times (and slowed it down) and if you look closely her hand clips the back of her head in the scuffle
If someone cba to highlight where Ellie and Hannah are on the clip that'd be great cause it's difficult to explain at the distant camera angle (I wish they'd stop using these in these instances). Ellie is at the back (furthest up the stairs of the group, and the closest to the camera - if that makes sense) and Hannah is below her to the right, with her back turned wearing pink and with a green thing on her head (sorry idk what it's called)
Pause the video at 00:20, then set the speed to 0.25 and watch closely, the hit happens at 00:22 and Hannah turns around (presumably in acknowledgement)