This is a quick and easy-to-build emergency shelter for surviving in the cold snowy enviroment. Often called a “snow trench shelter” or “snow trench cave”.
Preperably a real snow cave, a quinzhee or a slope cave would be chosen, but those shelters are time consuming and requires some experience to do right, and in som areas like in the forest, it can be impossible due to snow depth, or to find a bank with enough drifted snow. Shelters like that are more useful above the tree-line were there are more snow and less vegitation.
This one is quick and simple. Instead of boughs on top, you can use a tarp or any other cover. As said in the video, it is not very warm, not particulary comfortable either, but it keeps you away from the weather.