LOL, that video is funny, thanks.
[Removing filters for premium channels] never really worked on every cable system even decades ago when it was all analog. There were conditional access (colorburst/sync suppression, etc) systems in use even back then. And the reason for that is the same reason that it's used today.
It's simple to use filters to block channels above 100, or from 60 to 90 or whatever. But you can't just use a bunch of filters to allow an arbitrary set of channels through, it causes signal quality problems. Plus the inability to deliver PPV is a big problem for CATV company revenue. The conditional access stuff wasn't necessarily secure, though, so there were underground products that were used to bypass it (like image stabilizers/TBCs can bypass Macrovision)