I have seen shadow people many times, mostly while waking up from sleep paralysis with the feeling of someone is in the room.
I don't want to make up stories or memories but many times I felt that this thing that was in the room was not human and evil. It usually looked so dark, without any defining feature just a darkness (which was more dark than night darkness).
Every time I would awake from a nightmare or a sleep paralysis, I would see that darkness in front of me. But once I get fully awake it would disappear so I just forgot about it until I came in front of a site about shadow people.
When I read the stories I became dazed for days. It wasn't until later that I saw one very clearly. I was reading a book late at night when I noticed something from the corner of my eye. In those days and I still sleep in the ground or in the floor, I just don't like sleeping in beds. When I turned around to see what it is, I remember very clearly seeing a grey ball of smoke or what can be described as a grey orb as the size of football, more smaller than a football. It was transparent, almost invisible. When I looked at it, it quickly ran away and hid in the darkness behind a cartoon box where I used to put my books in. It looked like it was floating and running in the same time because it was so close to the ground and it didn't make a sound, it was so clear. I thought it got startled because I saw it.
I still feel them from time to time but I never seen them as clearly as that one. The last time was about six months ago when I had a sleep paralysis. When I opened my eyes while still in SP I saw like shadow moving very fast. I left the TV on that night because I felt they were around but just before I completely woke up I heard very clearly a growling coming from one of the side of the room. The closest sound I found was the growling of hippos. They were two consecutive ones but at much faster pace than hippos.
I couldn't come back to sleep so I kept listening to the Qur'an the whole night before I came back to sleep.
The story of your friend is somehow is similar to some of mine, the way that it was moving in a circular motion, I got attacked by dogs one time, they didn't bite me but they circulate me and they started to move in a circular motion around me, shadow beings act like that, one time before I slept I felt a shadow being hovering above me also in a circular motion, I even felt heat coming out of it, I also got paralysed I little bit, how can that be harmless, I believe it was just different type since there is a lot of type of shadow beings, (the orb- looking ones, the ones that look like clouds, the hooded figure, the hat man,,)
Their hostility also differs from one another, but that experience that that woman had is not completely harmless since she was paralysis when she saw it, shadow beings can cause sleep paralysis.