Kid throwing dog down a flight of stairs.

So I live in a six plex. My neighbors beside me is an older lady, I don’t know her. But she has a dog. Her dog was taken care of and looked clean, and healthy. Then I noticed her older daughter plus the bf and two grandkids started being here more often. NONE of my business honestly, idc. I started to notice the dog doesn’t look as well kept no more. His hair is long, his eyes have that brown discharge, ya know the stuff you clean off your dogs if they have it. But ya know not my business. Until today, the kids thought it be funny to play knock on my door and run off and laugh. It’s funny, it’s not harmful. I have a camera by my door. My front door is right by the laundry stairs going down. I checked to see who was knocking on my door, so I watched and I was like okay..whatever. But then I kept watching and saw the little boy(5-7) maybe years old. He picked up the dog, while his grandma was already at the bottom of the stairs, and he swings the dog and throws the dog down the stairs. Is it my problem? My place to even do anything? I definitely need advice on this. Bc I really do hate people who abuse or even let people keep abusing their animals. Thanks.