This take-off would be illegal in Canada today, but only according to fairly recent regulations. Just a few years ago, it might have been legal.
Here is what the Regs say, in this part of the world anyway
No person shall conduct or attempt to conduct a take-off in an aircraft that has frost, ice or snow adhering to any of its critical surfaces.
The key word is "adhering".
That definition is the same as it was 10 years ago and is still unchanged because when an aircraft is de-iced and anti-iced and it continues to snow, by the time it begins its take-off roll, the wings may very well be covered in snow, but snow that does not
adhere to the critical surfaces of the aircraft thanks to the anti-icing fluid. Before the new principles were adopted, (sept 1990 I think in Canada, following the accident report on the March 1989 Dryden accident) that same principle could be applied for dry snow: it did not "adhere".
After 1990, they had to keep the above definition but the philosophy changed, although I can't find the exact wording change in the regs they used to apply the new principles. .
When very dry snow falls on a very cold and clean aircraft (like when it's -25 Celsius on the ground) none of it sticks to the aircraft. One can blow on it and it flies off, leaving no trace on the surface of the aircraft. Back in those days, our spoilers were painted black. When we wanted to ascertain that our aircraft was "clean", one pilot would walk back in the cabin and look at the wings while the pilot remaining in the cockpit would raise the spoilers. If the spoilers were clean and free of snow while in the vertical position, we could take off, if not we would have to de-ice. They were painted black so that any snow or ice would stick out.
Russia is now where Canada was in August 1990 and everyone acts as though it was never done in these parts of the world.........
Here is a picture of such an aircraft with a black spoiler.......
