&gt; You might be talking about some kind of Spectravision-style video scrambling<p>I think that&#x27;s exactly what he means.<p>You&#x27;re right, it&#x27;s not intended to be cryptographically strong encryption in the modern sense. Scrambling (as I believe the term is being used here) prior to transmission often has practical purposes other than obfuscation, eg eliminating patterns in the signal that could interfere with the modulation scheme (for clock recovery). That it prevents casual eavesdropping is usually a side benefit, even though pay TV has tried to pass it off as a protection scheme.<p><a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Scrambler" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Scrambler</a><p>Here is an interesting report (attached in TFA) on how they cracked one of the transmissions containing digital video: <a href="https:&#x2F;&#x2F;www.documentcloud.org&#x2F;documents&#x2F;2699848-S455N-Redacted.html" rel="nofollow">https:&#x2F;&#x2F;www.documentcloud.org&#x2F;documents&#x2F;2699848-S455N-Redact...</a>