I didn't say yurts were cold, they normally have multiple layers of canvas (or similar material) that acts as very effective insulation. Air gaps are often better than foam. IIRC <3cm of air cannot convect, meaning from a well formed air gap you could be getting a far higher R value than an inch of extruded/spray foam insulation.
What I said was that ramped earth walls provide little value in a winter climate and are in fact extremely dangerous. >4' of dirt against a laterally unsupported foundation wall is actually illegal in my municipality. I see no lateral support in this guys structure. His walls would have to be incredibly thick (which they don't appear to be) to support the weight. The timbers need to go down a sufficient depth, which without the use of machinery, is unlikely to have happened and unlikely to have had the soil re-compacted properly.
What I'm saying is that the $5000 this guy spent on a 'house' is likely to collapse and kill whomevers inside the minute frost gets anywhere near his walls, let alone under the foundation or timbers.
A yurt on the other hand, due to its tent like structure and completely using flexible building materials would cope extremely well with differential frost heaving (which is what cleaves houses in two).
If the houses foundation doesn't extend below the frost line, you've got two choices. Heat it like you want it to spontaneously combust, because you want to keep the frost line well away from your structure. Or 2, ride it. I've seen many cottages here in Canada built on grade that have survived decades of winters because they aren't tied to the ground they simply move when shifted.