The guy in camo in the video is Bruce Naude, from my home town. I believe he has since passed away. He was one of our areas' "innovators" in what was kind of the predecessor of PRS ( think mid to late 1980's ). The .300 WinMag rifle setup was due to the ( at the time ) rules that you could only use what was actually on the rifle to calculate the correct bullet drop / drift on each stage. So, Bruce used everything but the kitchen sink. Plus, the big carrying handle to run with the rifle from stage to stage. He was quite good.
He was also the innovator of small, adhesive yardage stickers ( called "Target Tagz" ) that you could place on the target turrets of your scope over the appropriate hash marks to allow you to rapidly click to the correct yardage.
Kinda old school stuff but still kinda neat.