Not that this an excuse for what happened, but I don't think the video shows it well. It went from normal winter driving, with light snow flurries, to almost whiteout conditions in like a minute. That's what started it all off and why you see people coming up on the scene unaware. They were going too fast but you really couldn't see that far ahead and why people were just barreling into the mess of wrecked cars.
Irrelevant that the weather changed. The bolded part is what the essential problem was in that crash and most other snow crashes. Driving just too damned fast for conditions. And if the weather worsens, slow down more. Simple, eh?
No other excuse can be given. Driving too fast for conditions. Have no sympathy for the drivers in that clusterfusk of a pileup.
Heck, I grew up in the South and had very little if any exposure to snow driving until I left home and moved to the NE....MA, NH, NJ and DC areas. I never crashed one car during the years I lived up in those states. Why? I drove within the capabilities of the vehicle given the weather conditions. It's not exactly rocket science, after all, but a lot of drivers act like it is...or act like they've never seen snow or ice before in their lives and insist 55mph is just fine on a snow covered, slushy or icy road.
Worse is them riding your bumper and trying to force you to go faster because "they know how to drive in snow and how dare you go slower than they want to" idiots, like the idiots in the linked video. Never understood it.
For instance, 4 years ago I picked up an 18' V-hull boat in Madison, WI and drove it back to Cape Cod--I-90 the whole way out and back. It was January and on the way home hit a snow storm that started around Cleveland, OH, got horrible when I hit Buffalo, NY and stayed that way until I got beyond Albany, NY. My little Murano pulling that boat never missed a beat, but of course, I was matching what the semi drivers were doing---around 40-45mph during the worst of it, sometimes even down into the 30+ mph range. Meanwhile, we'd get passed by idiots trying to do 60mph. Eventually, we'd catch up to some of them as they'd be into the guard rails or stuck on the side of the road.
And I don't know how to drive in the snow, the northerners would say....because I drive "too slow".