Did you find an un-cropped version of the film clip?
I have been trying to do that for quite some time. Unfortunately without succes. In the photo most of the left arm of the guy with sunglasses is visible, which isn't the case in any of the filmclips I find.
According to this document, (page 2 below) the still was made by Johann Rush, who also filmed the scene.
http://jfk.hood.edu/Collection/Weisberg%20Subject%20Index%20Files/O%20Disk/Oswald%20Lee%20Harvey/Literature%20Distribution/WDSU/Item%2029.pdf
I used to think that the sunglass guy looked like Joannides. which would fit the Alpha66 and DRE connection.
But since I found this version, https://www.wpafilmlibrary.com/videos/108485 (at aprox.1:24),
I tend to believe, that he isn't a part of the group at all.
To me, it looks like he is just coming out of the building behind the ladies, as he moves slightly to the left before turning and walking away to the right.
Uncut and uncropped footage, if such exists, might tell us more.
/John
