Usually big corporations like Warn or Eaton (Detroit Locker) pay big sponsorship dollars to fund the events where the videos are made.   They also front the money to produce the videos.  Marlin is basically a mom and pop business for a specialized corner of the off road industry.

If you've ever seen any of Peterson's Ultimate Adventure series everyone that is invited is either a sponsor, magazine staff or a couple of readers.  The sponsors provide support and logistics for the event and parts to build the magazine's truck. 

Some of the best vids are the overseas "Winch Challenge" videos.