To be honsest, they were just lag. First one is simple to explain. On that person's screen, he could see you two together and was hitting in his view rapidly. On your screen it looks like he's hitting you from behind.
This applies to the first one too, but for the second one mainly, where they walk past you and looks like they hit you once they've went past is usually going to be lag, especially when you shorten the clip to that length.