I haven't had much experience on any modern snowmobile, but I'd have to say that the stunts that they're doing aren't for new riders, or riders who are accustomed to ditch-only riding. I am the queen of obviousness today! :)
The jumps may be easy enough - but I really don't think you'd want to screw up on that drop off. It would really suck to nose dive the sled completely, and do a helmet plant. Hmm...in that depth of snow, with it being that soft...there's a chance you'd be buried up to your waist with just your legs flailing around!
That'd be downright funny to see if there were no injuries and some people to help you out!!
Lastly, With a non-mountain sled, I don't think you'd have a chance in that type of snow!
/.02$