And who cares about the outside air temperature? All this 'if it is below -XX degrees it is powdery dry snow which will blow off' is nonsense. The wing temperature might be (and will be in the case of Airbusses with heated fuel returning from the engine) way above the air temperature. On the video you can see clearly that the fuel is so warm it melted ALL the snow sitting over the outer wing tank. The crew could have had absolutely no idea if the snow would blow off or stick closer to the wing root.
You know, this is the kind of stuff that will be okay for 99 departures, you can get away with it as the video shows. Other idiotic crews will see it and think 'hey, Sergei is a good pilot, he knows his winter stuff, I try also'. Well...the 100th departure might just dip a wing. You cannot get away with this kind of recklessness in civil aviation.