Not to say a tracked machine won't go farther in the mud, but they didn't prove anything in the video. The tracked machine had all the mud pushed out the way by the first machine.  Which could have made it if he'd put it in 2nd or rode the brakes to pull up the end, or turned the hog off to crawl the end when he was backing up.  Now if the tracked machine would have gone in new mud and floated on top, I'd say he proved the case.