Visible crew/equipment: During the scene when the confederate regiment begins to move up little round top, right after the "7-8 bullets shoved down the barrel line", a audio technician and boom mic can be seen to the left side of the image hiding in the trees. (01:57:15 - 01:57:50)
Visible crew/equipment: Lights from what appears to be the high school football field are visible in the distance during Pickett's charge.
Visible crew/equipment: During Picket's charge, shadows of camera trucks can be seen a lot.
Answer: Mainly because his soldiers were tired after a long march and he didn't think they could make a direct assault on an elevated position (the hill was not quite as "bare" as the film suggests). There were also reports of Union reinforcements arriving to the area, and Ewell was afraid that his army might be exposed and overwhelmed if he attempted to take the hill without assistance (Ewell had requested, and been denied, reinforcements of his own).