Show it, don't tell it.Philip is talking about why the Xero development team use screenflows and storyboards, rather than written instructions, to build each process within the software.
So I imagine that when they build, for example, the process of issuing an invoice to a customer within Xero, they have a series of pictures of each stage of what the process is going to look like.
If you've ever seen the bonus features of a DVD like "Wallace and Gromit in The Curse of the Were-Rabbit" (brilliant film - look out for the jar of middle-age spread!), and seen "The Making Of", there's usually a glimpse of the storyboards they use, the pictures of what the film will look like.
That tells the design team far more than a written description would. A written description might be confusing and vital bits might get missed out. With a picture, you can see it all.
And this is why screencast tutorial videos, for me, score way over written instructions. You can actually see what's happening on screen. You can see where the pointer is going for each menu. You don't have to muddle through wondering where the instructions meant.
But then I would say that, wouldn't I :-)