This is so simple. Watch the video, and you’ll see that from the viewer’s right, the initial event captured is that there come running up from the right one or more deer with the white-tail “flag” up (their built-in community alarm symbol), and at the end come even more running hard from even further back in the woods. So, something back in the woods spooked just one or a few deer, and his/their panic and running is what spooked the rest. When they’ve gotten a “good” distance away from the alarm center, and none is feeling a threat, they all stop and look around, to see if there is any new or continuing threat.
In the original 2013 clip, you can hear a vehicle. I’m guessing someone drove around and tried to get pics head on...and they reversed themselves.
This sounds very similar to what goes on in the financial markets almost every day.