I tried helmet covers, helmet liners, helmet earmuffs, balclavas, and headbands. None were all that comfortable, most seemed to comprimise the fit of the helmet, and none were really warm enough for Toronto, let along the Canadian praries where this guy is riding. Once I switched to a snowboarding helmet and goggles I wondered why I had wasted all the time and effort with the other stuff. With a neoprene facemask it works fine down to about -20C or so. I know it gets a lot colder in Regina.

I think it's just a question of finding one that fits. Most higher-end ski helmets do have vents, but they can usually be closed, a good idea.

Chin-guards are good protection, but tend to help fog goggles by blowing your breath up there. When I wear my full-face helmet in the winter I use a neoprene mask to direct breathing downwards away from the goggles.