Last June, fans of Comedy Central – the long-running channel behind beloved programmes such as The Daily Show and South Park – received an unwelcome surprise. Paramount Global, Comedy Central’s parent company, unceremoniously purged the vast repository of video content on the channel’s website, which dated back to the late 1990s.
You should probably read that wikipedia link. I built some of the blockers or stabilizers as Wikipedia article describes them. You could see the pulses described in the output of a scope that messed up the AGC in the VCR. All the blocker did was blank out the pulses and that was enough to prevent macrovision from working on the VCR when making a copy.