I've found some other shots that were actually released way back in September 15th, 2009:
http://www.flickr.com/photos/25792657@N00/sets/72157622254137443/
These two shots were on Nintendo's website as well, so I think the other shots from there were very likely from back then as well, just not shown anywhere else.
So the game potentially looks even better now! :O
Unless that dev video was from pretty recently, maybe December, still that's four months ago!
Also, I found an article about Frozen North showing the game last month at a school:
http://www.northjersey.com/news/89347057_Kids_get_sneak_peek_at_video_game.html
It includes an off-screenshot, very strangely, when you go to the page with the higher-res shot, and right-click it, it says it's protected by copyright law.
So go to the link to check it out, I don't want to rehost it or anything just in case (even though this is fucking ridiculous).
http://northjersey.mycapture.com/mycapture/enlarge.asp?image=28672507
Plus I found some concept art:
http://www.dancoxart.com/#2d_environments
The labels are at the bottom of each image.