She does it in pretty much every one of her scenes, in a way. It's not always focused on or the theme of an entire video, but you'll often see her balls do that whenever she gets head or a handjob, etc.
She's the best one to have this skill. I told her several times to do that when they suck her dick, and she told me that she always does that, but the pornographer doesn't focus on that, unfortunately For example, this video in which her balls are bouncing up and down