Without any knowledge about exactly when Towner was filming and when Darnell was filming this particular clip, and given the resolution of the Towner clip, it's all guess work and confirmation bias.
Well here could be another nail in the coffin, as the three people are walking across we see a man suddenly emerge seemingly running to where the 3 people are headed. This man in what could be a suit appears to be carrying something and it looks like he has a bag over his shoulder.
James Darnell doing his job, later in the weekend.
My interpretation based on Darnell's footage is that Darnell is the running figure who sees 3 pretty sad girls and tries to move into a position where he can capture their faces. And the lady on the right is the last one to step down from something, the path?
Having another look I think Darnell is filming shaky cam style as he is running/walking from left to right and this footage is only seconds apart from Towner, too bad there isn't a fraction more Towner so we can see the scarfed lady step down. And not only that but based on his speed, Darnel would be in front of the girls when the background monument would be in about the same corresponding position.
Another observation is that in Towner the girls are walking towards the steps and as Darnell arrives you can see the shadow start to appear on the vertical surface of the top step. And if you look at the above Darnell video you can see the middle girl take a step down then as the the scarfed girl approaches she next takes the step down.
JohnM