Modulating VCRs?

[Ed in Tx]

The Macrovision was recorded on the tape in the video vertical interval. I recall a VCR, a Hitachi-built GE in particular from mid '80s, that would strip out the Macrovision by inserting clean black horizontal lines over the Macrovision as well as the VIR signal. Like an external "video stabilizer" copy box. Thus the composite video out and likely the RF-modulated signal had no Macrovision or VIR signal in the video. As I recall the reason they did that was the timing errors (wow & flutter etc from the VCR playback) would screw with how the TV handled the VIR signal since it needed a stable time base to work right, if it ever did.