What strikes me about this video is not that the default position for tabs in Firefox 4 will be at the top of the browser (a decision I like a lot, by the way; I'll start using the toolbars I like more often, since the tabs won't get lost in the toolbars). Instead, what strikes me is that Mozilla is not only open about how they came to the decision (and how to change the default setting), they go very in-depth into the decision-making process.
That's awesome.