Apparently DVD players have "Macrovision protection" in them so don't hook it up to the VCR
It sends a signal to your VCR that will scramble your picture

Macrovision breaker boxes are common and relatively inexpensive. For people who don't have video inputs on their TV set (antenna only) and they have to daisy-chain the DVD player through the VCR in order for it to work (our old TV was like this), you have no other choice but to use a macrovision breaker box.

Also, it doesn't scramble your picture, it just makes it slowly fade from light to dark and back again. Still irritating.