Who remembers this?
Back in the day C Band Satellite TV was like the wild west. Most transmissions were analog and in the clear. Many enthusiasts and shops were getting into the new era of tv at the time. Time Warner who had HBO, Showtime, The Movie Channel, etc was not about to leave it all up for free and this did not set well with most of the free spirited satellite folks.
Taking over a FM signal like Captain Midnight did is relatively easy to do on a FM signal and the associated receiver's limiter and demod system can be over taken with a signal of about the same center frequency and a level of about 3 to 4 dB higher RF wise than the intended signal. This is known as the Capture Effect. Google FM Signal Capture Effect if you want to learn more, it is a fascinating subject.