said by rradina 
:I believe they use "off screen" video scan lines to overwhelm the automatic gain governing circuits on recorders. Although your TV's presentation of the signal is unaffected, a recording ends up with wide swings in brightness which makes it too irritating to watch.
Whoa, that's what Macrovision does? I've had a couple DVD players that did this while hooked up through a VCR to a TV that only had a coax input. The guy at Radioshack made up something about reduced power output of the new DVD players. I now hate Macrovision.
