I tend to agree,
Gary Mack's own observation that the shape is "moving toward the street" came from a very low quality gif and not the the SFM's copy of the film
which he could have studied if he wanted to... and I think he was mistaken.
The camera moves so much between the two frames where "the smoke" is seen, that nothing stays the same, or still.
Looks good in that one Wiegman "limo frame" but Willis6 looks better.