It's hard to see what is actually going on here, but it looks like Don King steps out of the ring at the very beginning of the video and makes his way to the corner where he is met by a woman.
While this is going on, HBO is also filming a post-match interview with Bermane Stiverne after his unanimous decision over Chris Arreola. As soon as we see Stiverne, King and the woman—who looks like some sort of credentialed official or perhaps security—appear to exchange a few shoves and shouts. It's unclear if she is merely preventing King from getting to who is actually yelling at or if the altercation is with the woman.
The altercation comes to an abrupt end when King falls from the ring and lands right in the middle of the interview.