No BS.
This would have been something very doable 15+ years ago when I was shooting alot of buffalo rifle and 308 bolt rifle with open sights. I was able to see the sights, targets, and could shoot very good when everything came together for me on that day. Some days were better than others, but normally things were good for me.
The 45/70 made the 308 seem like shooting a laser that didn't need elevation.
They were just using a radio/mike on the steel, just like we used to to verify hits. The video just helps make things see-able for us.