Prairie dogs are a nuisance and there are many reasons that their population needs to be controlled, just one of which is their ability to completely destroy the crops we depend on for food.
Oh and about the guns they were using, I found this:
Q: What the @#$% did you shoot those varmints with?
A: Well, this varies. We use the following calibers in our 2 current titles: .17 HMR, .204 Ruger, .223, .22-250, .243 Ackley Improved, 7mm Rem. Mag, and .50 BMG.
The majority of kills in “PDBG!” come from the .223 and .22-250.
In “DBG&B!”, it’s mostly the .243 AI and .22-250 on Rock chucks and Ground Squirrels, and the .204 Ruger and .22-250 on Prairie Dogs. More important than caliber though, is the bullet design. Almost all of the varmints in both videos are hit with highly frangible bullets, such as the Hornady V-Max, or Sierra BlitzKing. This is what really causes the extreme reactions you see.