Cool, though I'd hate to see the clutch afterward if the truck had been seriously stuck. I won't risk trying to pull that thing out of any ditch with my Subaru.
I did that once with my Land Rover. I had to snatch it an inch at a time with a chain and it stretched the chassis, none of the doors would shut afterwards, I had to bungee them together till I could get back to the garage and reposition the rear body forward a bit.
? It is actually a regular thing on series 1, 2 and 3 land rovers, pre 1972 or so when you were pulling big loads because of the way the door catch worked, it was just like a normal house door so if you moved the bulkhead forward or the back body box back the doors didn't reach the catch. It was rated to tow 3 tons but would actually pull around 25 in FWD before the transmission trashed.
I find that very hard to believe. I had a wrx, and yes they are capable in the snow, but not for towing, especially a semi.
It looked and sounded to me that the truck was still doing most of the work, and the Subaru was just adding some boost. It wasn't dug in or seriously stuck.