VHS to DVD question

[Dave A]

MacroVision is in the vertical sync and you can see the white markers going in and out randomly as you play the tape. At it's max brightness, it is well above 100 IRE of video and the copying VCR AGC tries to correct for that. When it does, the sync level (from 0 IRE to -40 IRE) of the VCR also collapses and the recording is now unstable.

The copy guard boxes also inserted a box of it's own in the sync effectively covering up the white markers

Andyman is correct after a fashion. Betamax machines always inserted new sync pulses on it's recording, effectively stripping MacroVision right off. Most VHS' just copy whatever...including sync...is coming at it. You would have to look around at the schematics of older VHS to see if any did the new sync thing.

If you still have a Betamax around, but need tape stock, you can use broadcast Betacam Oxide tapes in the blue shell. Same thing.