Retro VHS runs your word through a tape that has been played too many times: the colour channels separate, tracking errors tear horizontally across the frame, and scanlines roll continuously through the whole thing.
Driven by SMIL rather than CSS keyframes, because the tracking errors need to fire at irregular intervals rather than on a fixed cycle. feTurbulence generates the tape noise, feDisplacementMap tears the image along it, and feColorMatrix pulls the red and blue channels apart the way a failing tape head does.
The turbulence field moves, so the tearing lands in different places through the loop. That irregularity is what stops it reading as a repeating CSS effect.