I got this story last week from her majesty, and got a lot out of this article. Best quote (last sentence is the key):
The main guideline for a scrollbar’s look-and-feel is simple: Use your platform’s standard scrollbar, which is what users know and expect. When designing for Windows, use Microsoft’s widgets. When designing for Mac, use Apple’s. And if you’re using Flash, use the standard built-in GUI components.
That implies to me that Jakob Nielsen is recommending to use the v2 component framework. It’s really nice to see Jakob helping us Flash designer & developers, specifically. Thanks, J!