How would one go about making a consumer equivalent to this quadruplex control track recovery system (https://www.youtube.com/watch?v=M9lSMRlS73s)? There doesn't seem to be much detailed info on it.

Other methods are less sophisticated and ignore the video signal. I've tried the double A/C head modification listed here (https://web.archive.org/web/20220228180656/http://digiommel.fi/Issues.html), but it fails to quell larger dropouts and can even cause interference under certain conditions.