Reading through their mail merge tutorial, their method looks insanely risky: putting all addresses in “to” and rembering to click another button.

I meant it more in the sense of one channel, when shutting down for the night, emitting the “next channel” tone such that every viewer’s set would change to a channel that was still broadcasting.

Would it have been possible for the speakers of the time to emit those frequencies? Imagining the equivalent of a Twitch raid: “I’m done broadcasting so I’m going to send you to the next channel.”