You have to be careful with extended editions as sometimes the beeb don't broadcast them or make them available online. It happened with the last series of QI and a couple of editions of HIGNFY.
Sometimes they can have 10-15 minutes of drivvle that was rightly cut out of the standard edition.
It's it the editors job to go through the material and give the viewers the best possible 30 minutes.
Saying that, I usually do watch the etended editions just incase there is a good bit that the editor didn't think was relevant to the show or went off on a tangent.