The video is mainly aimed as being a piece of viral promotion for the Lumia 920 and the Nokia Design team, but it does offer some insight into a process that isn't always as appreciated as much as it should be.
Ahtisaari opens by talking about the principles underlying the design of the Lumia 920:
"We've created a really beautiful balance between the digital and the physical. We take everything unnecessary away, and you're left with only the essentials. In this case it's a product that made out of two pieces: the polycarbonate monobody and the piece of glass that flows into it. We pay a lot of attention to all the details that remain: the ceramic details on the keys, the way the glass the display fold into the body of the phone, the way every single detail is finished."
And goes on to talk about some of the motivations for design and what this led to:
"We wanted to make it built better, that means it's solid, feels like you can take it outside without covering it in bulky covers. We wanted to make it human. And human means our products are never cold. And even as this product, from the font, looks like it has hard edges, nothing could be farther from the truth. When you turn it around it's extruded shape, tapered ends, feels kind of a pillowy... it feel organic, natural, maybe even supernatural in how it's made. Sometime we say, as a product, it could have grown out of nature, or grown on a tree, rather than off a production line."
In other words the design team wanted to stop people putting ugly covers and cases all over their hard work... seems reasonable to us!