The only reason the snow blew off is that they held the plane on the ground for an extremely long time, increasing the wind speed as much as possible before they rotated (and even then it is the most idiotic thing I have seen in years). What if they suffered an engine failure and had to limp it in the air with one wing still covered with a lot of snow?
And with Checkboard I agree that there is no way to see from the video if the wing was clear at all. There probably were a lot of rough patches of clear ice left along with the spots of snow that did not blow off at all.
Bavarian, I am as shocked as you, but there are still idiots around, and I'm not talking about these Russians, who think they can get away with not de-icing.