Lucille Ball Long, Long trailer

I always wondered how they could pull that big trailer with a sedan. My wife recorded it and I watched a little more carefully. They had a two wheel hitch dolly under the trailer tongue and I think they had one of those hitches where the pivot point was at the differential to eliminate sway. I've never seen a hitch dolly used towing in real life but I have seen a lot of people that could have used one.