You can watch the movie for free via Amazon Video (Freevee) right now.
Some explanations fro the scene (contains spoliers!):
Five girls are sent to a school because they are - well strange. Think X-Men, just with this being a horrendous religious school (at least that's the impression in the beginning).
The headmistress secretly wants to sacrifice them to a demon called Legion. He took possession of her sister some years ago at the same school and she sort of struck a 5 lives for one - deal with him.
So if you see moving things around during the spanking - this is the special power of the spankee "Alex".
If you are wondering why she takes the blame although it was "Mara" who broke the rules - I don't know. It makes absolutely no sense; not much in this movie does.
Anyway, to my mind it would have been much better if Jordan Madley as Mara would have taken the spanking. She gives me more of those "bad girl who might even enjoy it" - vibes.
Mara's power is healing and it can be seen afterwards when she makes the bruises go away. Spoiler: She is the only one who survives.
Is it worth watching? No. While production values are pretty good and Ron Perlman plays one the main characters the movie fails to raise any interest in its characters and the plot has more holes than a golf course. After one third of the movie the whole thing really starts to go downhill fast.
