They've edited out the cliffhangers, airing it as a single story instead of four episodes. I'm curious why they didn't grab the cleaned up version from the DVDs. The broadcast version if awfully faded and washed out. It's very much like the "before" version of the feature that's on the dvd, showing before and after clean-up.
Ah, I remember reading somewhere that the reason we rarely see the DVD versions being broadcast is because it's a tricky rights issue. The team which does the remastering provides fresh digital copies of every episode to the archive, but these digital copies are owned by a particular arm of the coporation, and are not licenced for public broadcast. So if they did
broadcast them, they'd have to negotiate an extra fee for the use of them. It's cheaper to use the already existing broadcast copies, as they are owned lock-and-stock by the BBC.