There is a similar case with Top Gear. Aside from the popularity of Clarkson/May/Hammond and the fantastic cinematography, the show had great editors with an ear for soundtracks. Unfortunately it seems a lot of the tracks were only licensed for broadcast TV and the DVDs have some stock music where the rights were no longer available. There are also some gags which don't work any more because the audio doesn't make sense.

I believe the only place you can watch them as originally produced is iPlayer, but at least the BBC has copies somewhere.