I'm going to ask what may be a really stupid question.Some photos from the shoot in question which confirm at least some of the claims:
Why does Doctor Who do so much location shooting? Do they not know how to build and use soundstages in Cardiff or something?
There's a lot that can be done now with greenscreen and virtual location shoots, like this. If the BBC were serious about keeping spoilers under wraps, they wouldn't film the show out in the bloody open.
Interesting vid. It'll be cost I'd wager. Would be nice to see more visually interesting scenery though...