How do Ты do that?????

Hi. I'm trying to isolate a tiny area of a video clip featuring Snape (of course!) during the duelling scene right after Lockhart lands on his back. If played in slo-mo, it looks like Snape is sort of 'rocking out'. Maybe he was just stepping back - but he was stepping back with style! Anyways - how can Ты isolate that portion of the clip to make it an animated icon??