Compared to the Merc in the video above, the 4MATIC in the A, B and CLA will be quite different. The torque split is around 50-50% by default in the bigger Mercedes, and 4MATIC adjusts power to the front and rear from that basic setting.
In the A, B and CLA, the torque split default is 100% front and 0% rear, and the torque only begins to be applied to the rear wheels if the fronts have begun to slip. This is the so-called Haldex system.
The resulting handling characteristics will be quite different, especially when driving fast on compact snow, where the handling limits of the Haldex cars will be lower.