Even now you sometimes see 24fps material not sped up- when I recently caught the Channel 4 morning showings of Cheers (now using HD masters rather than the poor SD ones they used to use), it wasn't sped up, but with some iffy looking motion.
I've also seen some US 60i content with some incredibly jerky motion over the last few years, almost as if they've treated it as if it was 24p with 3:2 pulldown and removing every 5th field even though it's actually full 60i motion. It's incredibly poor standards conversion whatever causes it, especially as we're now in a digital HD era.
Watching the BBC4 TOTPs, as we're in the era the US version was running and they showed some performances from it, you can see how poor the picture quality is on those performances compared to the rest of the show.
And I seem to remember reading when BBC2 first started showing Laugh-in in the late 60s, it was shown with a black border round the edge, presumably that's how the standards converters they used worked? Must have been one of the earliest US videotaped shows shown over here.
Yes, I remember the first series of ‘Laugh In’ being shown with a black border around it, in fact the continuity announcer would often make a point of saying something along the lines of ‘and now on BBC 2 it’s time for small screen time as we join Dan Rowan and Dick Martin etc etc”. I suppose it was to prevent viewers thinking there was something wrong with their tellies at home, would make perfect sense.