[rupertj]

I'm from England, and his accent in that video sounds pretty neutral to me. It's got a bit of a "posh" or "well spoken" edge to it, but in terms of region, that's going to be somewhere around the south of England, excluding places like the south west and parts of London, which have distinct accents.

[laumars]

I agree.

Occasionally you'll find extras which sound Welsh, because the show is filmed in Wales. But for the most part it's a very neutral accent. Even Amy Pond's accent isn't particularly strong.