Sorry shortwave, but your post wasn't unclear. There are light spots on the back of the head where you said they would be, LOL.
Yes there are light spot on the back of the head as you suggested. Unfortunately, that's not where I was referring to
If you look at the beginning of the vid. where the smaller deer is at the very left of the screen, you'll notice at one point where the deer quickly throws its head straight up in the air.Snout straight in the air.
Start freeze framing just before that happens and you eventually get a shot of the whole top of the head. Your looking at it from kind of a rearward top angle. But you can still see clear to the eyes including the frontal area where the antlers grow from.
Again, don't know if that area looked a bit lighter due to lighting or if in fact it is lighter.
Never-the-less, I wasn't claiming the smaller deer IS a small buck. Just suggesting the possibility from the freeze frame and its actions.
What ever the case, the smaller deer, doe or buck, looks to be very young.