I have these for our camper and it is a world of difference with leveling. They are as easy as they say. I get the trailer close, put them under the tires, back up a little more than level, put the included chocks in, and pull forward a little bit.
I have used them on grass, soft dirt, gravel(didn't even put a mark in them) and have not had one problem with them sinking or anything else.
Our current method is to have the wife stand on the side while I back on the levelers, similar to the video. I would like to put one of those fifth wheel levels on the front of our camper, but because it has a curved front, I am not sure how to mount it.
I know they are pretty pricey, but well worth the time it saves, especially when the kids are screaming.