Very nice video. We've done that a few times too. The only difference is, we use a port-a-potty instead of a cassette toilet. And we select State Parks that still have out-houses so we can dump the port-a-potty.
I do totally agree with one thing though in that video ... when camping that way, you are the only people there! The solitude is magnificent. And the nights are dark with no electric lights from other campers blaring away. On a snow covered countryside, the moon light shines as bright as day! Winter camping, in the snow is not for everyone. But for those who do it, it's awesome for sure!