Haven't been able to watch this yet, maybe you can look at their movement for inspiration: http://www.whiteparkourvideo.com/
Last year when I first started parkour, I basically quit during the winter for almost half a year. This year, I'm determined to do something just about everyday. Last Saturday while it was snowing, I practiced single leg squats, power cleans, muscle ups, pull ups, dips, push ups, rail balancing, uphill sprints, and precisions (all outside). There really are a lot of things you can do in the winter, even outside. I think the reason I gave up last year was because I thought parkour was all about vaults and it was difficult to do them when wearing bulky cloth. Also I didn't really set any goals for myself.
SNOW is just another obstacle to get over.