The narrator would have you believe this is some new technology. When actually it is not during WWII the marines had a tracked personnel carrier called the LVT or landing vehicle tracked. The LVW which was the same as the DUKW the Army had These wheeled vehicles were based on the 2 1/2 6-wheel drive cargo truck chassis.
When I was TDY at Aberdeen Proving Grounds in 73, we were testing among other things a 5-ton amphibious cargo truck in the Chesapeake Bay. What a nightmare those things were Everything was pressurized the transmission transfer case the diffs even the cab doors they would float as long as you had exactly the right amount of cargo or if less than 3 tons it had to be loaded as far to the back of the cargo bed as possible, or it would nose down. more than 4tons it had to be distributed evenly throughout with only 12 inches of freeboard when fully loaded the smallest waves would spill over the sides It was based on the M813 cargo trucks. I don't know which version if any finally made it through testing I doubt if the one, we drove did since we sank it about every day in 8 ft of water then had to drive it out as if it were a simple cargo truck with a fording kit installed.