In the slo-mo version someone posted, some of us could see his mouth open and shut a couple of times at least, in a way that looked like he was talking/mouthing words. He had turned his head slightly to the left when he did so! That's just the way it looked to a few of us. It took me by surprise and creepy to boot!
I can't even see a defined mouth. But then again, people saw the reflection of jodi arias in Travis Alexander's eyeballs, in the photos of him in the shower, and they saw the impression of the face of a screaming Caylee in the stain left by her decomposing body in the trunk of her mother's car.
I couldnt see any of that either.
I don't see dogs or guns or specific outfits (except blue jeans and a dark jacket, something tan at his waist and on his head) or any defined facial features whatsoever in that blurry image, no matter how many times people blow it up or try to sharpen it.
Regardless, people who are talking while walking typically have their faces pointed upwards, even when they're talking to themselves.
Just because the blob where a person's mouth is supposed to be, may appear to some
to move, doesn't mean they're talking. And it wouldn't make sense for him to be talking to the girls at the distance he would have to be for Libby to feel comfortable recording him (and based on the lack of definition), anyhow.
His body language shows a man who is walking forward in a manner that is supposed to be unconcerned with, or not noticing the people recording him. My belief is he was walking fast. He likely kept his head down because he was trying to bridge the distance before confronting the girls.
That would make anyone uncomfortable I think. Someone silently ambling up fast, directly toward you but as if they don't notice you, when there's no way to miss you.