What surprises me about that video, is not that the gun/round shoots at 1000 yards, but that people are surprised it did so.
I've studied sniping for a long time. In doing so I've seen the list of the Most Confirmed Kills by snipers throughout history, at the top of the list were the Russian snipers using Mosins and the 7.54X54r. These were not the high powered, high tech stuff you see now, but they were War Time Production rifles, Most even by WWII Russian Standards weren't sniping rifles but standard service grades. (The all time top sniper was a Finish Soldier in the who didn't even use a scope).
If you get a surplus 91/30, with a decent barrel, and load it with good components, (there are even match quality .311 bullets out there) it will make a quality target rifle without a whole lot of modifications. The one thing that I don't like about the Mosins is their lack of ability to make quick windage changes via the sights. But all in all, its a pretty good system, proven by the fact its the longest surviving military rifle out there, still being used to day in precision shooting and combat.