HBP: Swing or no swing?

[Andy]

I have had situations much as you describe where the batter, who is trying to avoid the pitched ball, has the bat come around and look like a swing, but it is more of a defensive move. It's one of those "I know it when you see it" things and hard to describe.

That being said, in the video presented, I would have ruled a swing. I don't think the batter being hit by the pitch is what caused the bat to come around. If he had not been hit, it seems unlikely that he would have been able to check his swing.