Last spoilery update, I swear!
Added 2019-01-29 20:48:41 +0000 UTCAlright, I finally found a source that outlines time-lapse VCRs well.
It turns out that the most remarkable thing about time-lapse VCRs isn't in the heads, but in the capstan motor. It needs to have extremely precise control because when recording, the heads actually write to the tape while it's moving and they are inactive when the tape is still. So, the signals on the tape actually end up being completely normal VHS signals, with the right angle and everything. I may even be able to get some good slow-mo footage of this with my phone.
What's less clear is how it does this in the 12 and 24 hour modes when the tape is moving, but at the wrong speed. I'm guessing it uses its four heads to its advantage to more-or-less get it right, and then during playback it's wonkier because it has to display the single frame multiple times rather than the single shot it made when it recorded. That's a little fuzzy but it is explained in the document. I just don't really get why quality improves with the stepping motion and audio off when during recording it was a smooth motion.
Anywho, here's a link to that source if you'd like to take a peek!
https://books.google.com/books?id=ysg7w5aGDzEC&pg=PA167&dq=%22time+lapse+vcr%22&hl=en&sa=X&ved=0ahUKEwj3usi3zpHgAhWn7oMKHXwCCqMQ6AEIMTAB#v=onepage&q=%22time%20lapse%20vcr%22&f=false
(you'll have to scroll around a bit to see the relevant parts)
