I think that's it.

I assume the pint glass pops up at intervals that the investigators would know and the general public would not, so you'd need some kind of central service with someone watching the commercial stream and showing/hiding the pint glass at the right intervals. In which case it would make more sense to operate a central service just pirating the commercial stream, which I'm sure does happen and does get shut down.

>I assume the pint glass pops up at intervals that the investigators would know and the general public would not,

This would be the smart way to do it. But now think about how you'd do it the lazy way...