yeah, but jumping jacks produce light, whereas nothing here does. It's not like people are snapping flicks at streetlights, there would need to be a source of light to "drag", no? These are just pictures of the open immediate sky above an open field, with no lights. Unless I misunderstood your post... but even if that is the case, it doesn't account for why such a high percentage of pictures taken there during vigiles have this effect, as opposed to somewhere else. I literally saw thousands of pictures. Surely it can't be just something as common as a photographic error or this would be happening to people elsewhere as frequently as it happens there.
There's also pictures like this from the scene, which may just be a blend of two stills into one, I'm not sure I'm qualified to tell...
and then pictures like this...
that last one especially I have a hard time chalking up to shaky hands...