There are two video recordings of "Halfway Down The Stairs", both performed to the same audio recording of the song. One has yellow/brown lighting, the other has blue/purple.
At this point, it's not clear why there are two takes. My copy of the German cut of the show uses the yellow/brown version, and my UK cut uses the blue/purple one. One theory is that the second version was recorded to use on "Top of the Pops" in lieu of performing the song live in studio, although why they chose to re-shoot it rather than using the original take, I don't know. At any rate, "Top of the Pops" used the blue/purple one (so far as I'm aware).
Regardless of the reason for making the second recording, it ended up being edited into the episode at some point. I should note that my German copy of this particular show does not match my UK copy exactly - there are numerous single-frame edits and a couple of 6-frame trims to the German version, which suggests that the show was re-edited pretty much from scratch at some stage, with the blue/purple take used. I can't confirm the age of my UK copy, so it's entirely possible that it's a later edit than the one originally transmitted in 1976.
So far as I'm aware, the yellow/brown version is the earlier of the two. In any event, the audio remains the same, so it doesn't really qualify as a 'German exclusive' in the way that the Mary Roos song does.
If anybody knows the reasons for this second recording having been made, I'd love to hear from you!