IIRC some products even had the unintended consequence of removing it. I believe my mother copied those tapes using her camcorder to play the tape into the VCR

IIRC some products even had the unintended consequence of removing it. I believe my mother copied those tapes using her camcorder to play the tape into the VCR which was recording. That's how I recall it working anyway, I don't think she had any special piracy/filter hardware.