I saw the video too. The woman was wrestled to the ground. The guy pushed her down with his foot on her lower back, which slipped to her head, in a way which seemed to be attempting to communicate to the woman "you stay on the ground and stop trying to get up", rather than a stomp intended to injure.
In these days, somebody approaching a candidate in disguise with an object is likely to be treated roughly. That said, the video is not helpful to Rand Paul's side.
Foot on her lower back that slipped up to her head? Get real and take another look. I guarantee...that guy will be in handcuffs as soon as he’s identified.