Anybody know what the whining noise is?

I believe that noise is the inflation system for the backpack.

Hmmmm....so they inflate with a pump now, not compressed air canisters? Progress.
(Looking on their website, yes, they use a battery operated pump for multiple deployments and to make it easier to get on planes, with no compressed air canisters that may be denied).

*nsfw

This video has been flagged as being Not Suitable For Work - declared nsfw by Mekanikal.

Man, the speed he passes those trees. Lucky not to hit anything on the way down.

And the best part is that little snowball that came tumbling down the hill....

I thought the noise was a noisemaker to attract attention in case the user was incapacitated.

Guess you have to deploy it before you go under or it'll just get filled with snow.

Here's what the backpack looks like as it inflates:

Just for the record.... the snowboarder shouldn't have ridden that line. Sure, he had an ABS backpack... great, but he didn't read the terrain.

As easy as it is to criticise in hindsight there were plenty of signs that he should have read (recent natural avalanche activity, convex rollover, the Avalanche Canada report) that should have said "stay away".

I'm not trying to make myself sound smarter than this guy. I still consider myself very much a beginner in the backcountry, so I take as much care as possible, including knowing and trusting the guys I ride with.

Bottom line: you should be looking for reasons NOT to go.