Looking at it again it says. "The Scot will dovetail his new commentating duties with his ongoing punditry role alongside ex-team owner Eddie Jordan and the Beeb's anchorman Jake Humphrey." So it seems he'll do the pre-race coverage, run to the commentry box, then run back to do the post-race coverage. Even looking at the original crash.net report (which I should have linked to previously, here it is) the only thing which holds any weight is, "a BBC spokesman told us that "we're still looking at our line-up for next year's F1 coverage'" the Coulthard stuff all seems to be speculation from "a reliable source". I don't know how reliable this website is.