The Group Shred from All I Can
Janill Gilbert stashed this in Ski Porn
Amazing work with the filming and editing.
Dare I ask what a group shred is?
I guess shredding is also a reference to music
"Shred guitar or shredding is a lead playing style for the electric guitar, based on various fast soloing techniques. Critics have stated that shred guitar is associated with "sweep-picked arpeggios, diminished and harmonic minor scales, finger-tapping and whammy-bar abuse."
The shredding around the skier/snowboarding world, means to aggressively ski/board the hill, it looks like the term originated in the skateboarding community. You can add gnar (gnarly) in, and you get even more interesting skier/boarder lingo, as in, "Whoa man, you were really shredding the gnar hard, when you launched off that cliff today."
Some interesting banter about the phrase "shredding the gnar" http://www.epicski.com/t/115347/what-is-the-fun-in-shredding-the-gnar
So a group shred, is a bunch of skiers/snowboarders hitting it hard, aggressively skiing/boarding the slopes.
Wild -- it seems like skiiing is a sport where aggression is dangerous.