Dog abuse??

So I have a door bell camera outside my door I can see when motion is detected and it records so I watched the video and I see this guy standing in front of his dog I can’t hear what is being said but I just see him repeatedly hitting the dog in the face and the dog is looks scared and I don’t know what to do I can’t say nothing because I feel like they will know it’s me saying something but I just feel for this dog this dog needs help I don’t know what to do