Does this qualify as an air gun?

That is so cool, Almost makes me wish it would snow more around here... 

It's using some compression of air in the tube behind the snowballs to accelerate them out the tube, so yes, I say it's an airgun.
Dictionary definition: "a gun that fires pellets using compressed air."
Now if someone could make one like it and take out a crow or two, that would confirm its status as a true snowball airgun ;-)

For crows and big game all you have to do is switch snow balls with ice balls.