What would cause this wonky camera work in an old TV show?

Found an old episode of the 1971 London Weekend TV series “Doctor At Large” on YouTube. It’s in Black & White due to the 1970/71 Colour Strike, which in and of itself is one bizarre concept, but not really relevant here. Starting around here in the episode, while the show’s characters in the forefront remain (mostly) stable and in focus, the background wavers up and down in a sea-sickness inducing pattern (the background is stable for seconds here and there, mostly when everyone is stationary).
Since I doubt LWT at this time used digital filming technology (actually the proof is that this episode is B&W and the workers simply turned off the colour tubes during the colour strike), what optical properties in the field of analog filming would have been causing this?

ETA: Not really Café Society material, as I am interested in what’s causing the effect, not the history of the series or actors.

I’ve seen that kind of effect with the smaller cameras used in the field for news, but never with large studio cameras. With a small camera it’s usually a combination of a jerky manual zoom and a physically unstable camera.

However, large studio cameras are on large dollies and, even in 1970, had power zooms. I suppose it’s possible that, rather than using a large studio camera, the producers might have substituted manual monochrome cameras. It’s possible the camera operator simply wasn’t familiar with how to use a zoom lens, but that doesn’t explain the picture suddenly tilting then straightening.

There’s no reason to throw out the digital angle just 'cause it’s old stock. I would suggest an errant and badly-chosen digital stabilization routine was let loose on the video. Note that it only happens when characters are moving around - it’s probably trying to keep them still.

Youtube offers to “stabilize” video it thinks is shaky… possibly it got screwed up at the last minute. (My GoPro footage gets this offer often, which due to the content leads to strange zooming effects. On content from a film stage I can imagine it might do what’s in the clip)

That is weird.

I think Nanoda’s right, some sort of post stabilization software was run on it on any shots that were particularly shakey or jerky.

Can you find another source for that episode to compare?

This also raises the question of why such rough camera work; especially the ‘seemingly’ locked off shots of the old women complaining to the doctor. Maybe they only had one tripod, and just went handheld on some shots.

Yep, its the stability algorithm picking the black and white penguin as the thing to hold rock solid…

Its probably passed a threshold test for “large shadow”. Is there a large shadow ? True ? then hold it steady !

I was just going to reply that it looks like a digital stabilization algorithm being applied, but I see others have beat me to it.

Thanks for the responses so far.
I hadn’t considered (40 years after the fact) post-production digital processing (either for DVD remastering, or when ripping the program from thereof), nor had I thought about any processing which YouTube might apply.
Just to note, there was another episode with similar wavy background, but some following episodes were fine, stable backgrounds and all.