You gotta go with Supervention, Being There (both by Field Productions), All.I.Can and Into the Mind (both Sherpas Cinema). Supervention is probs one of the best ski films I have seen and gets you so pumped for winter. I would highly suggest it.
If the best (keep in mind I'd rather watch pow and park than any kind of urban):
Teddybear Crisis (MUST WATCH IF YOU HAVEN'T)
IDEA, Hunting Yeti and After the Sky Falls
x=10, War, Ski Porn and Twenty (my favourite PBP)
Shanghai Six, Long Story Short, Turbo (my favourite Level1)
Blizzard of Ahhs (Old school skiing is awesome)
Light the Wick