(Apologies if this is the wrong stackexchange, it seems the most appropriate)
When rewinding a VHS tape on an analog player (i.e. a VCR hooked up to a (CRT?) TV) when rewinding, or fast-forwarding, and regardless of video format (NTSC vs PAL vs SECAM) we're always treated to the same effect: a relatively clear window into the video playing backwards (or forwards), overlayed with two or three bars of static. I found a good example on YouTube here (around the 00:06 - 00:10 time):
What causes this? How does the action of the helical-scan tape over the read head cause these artifacts?
I also wonderred: when rewinding, if the VHS tape is playing backwards, and the video signal is scanned one scanline-at-a-time, how is it the video display is not vertically and horizontally inverted? Even on early, pure-analog VHS players lacked framebuffers yet when rewinding their displayed the video in the correct orientation, how was that possible?