Presumably it was the tape that degraded over the decades (perhaps stuffed in a box, moved from house to house, thought of as junk until they had the idea to post it on the internet)
I said this upstream, but I have clear memories of borrowing tapes of stuff people had recorded off their tv in the 90s and having exactly these kinds of glitches. I think we're seeing the difference between a professionally recorded vhs and a home system that someone just learned how to use.
Analog didn't have an "XxY" resolution. VHS was about 3MHz of luma resolution and 400Khz of chroma, which was 240 lines - but that was interlaced, so your actual vertical resolution was 480 lines per interlaced frame (30 per second at US rates) -- but your Y (luma) signal would change far more often than your Pb and Pr signals (which gave the color by recording how far off the Y signal Blue and Red were)
NTSC has a nominal resolution of 720x480i (240 lines per field, 60 fields per second). VHS on its best days could get about half the horizontal resolution for luma, and even less for color, but often ended up a bit worse, so 320x480i is probably a good approximation for the resolution (ignoring the fact that color is even lower resolution).
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On a slightly different note, the HiFi audio track (supported for playback by pretty much all VCRs by the late 80s; not sure if/when HiFi recording became normal) of VHS was undoubtably the highest quality consumer analog audio product to get wide usage, with an SNR and dynamic range slightly better than the very best cassette decks.
Maybe, but as I remember it, VHS looked much better than analog TV from the same time. I remember being marveled by how clear it looked in comparison (mostly because it did not have as much noise as analog TV did even with a good antenna).
My family didn't really mess with VHS recording growing up, but I do remember getting shitty tapes from friends' families who had recorded stuff off tv and seeing glitches like this. Could just be the vhs player/recorders didn't work as well as professional ones?
